Form 485APOS VANGUARD INSTITUTIONAL

Fund Summary

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization stocks.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Institutional Shares or Institutional Plus Shares of the Fund.

Annual Fund Operating Expenses

(Expenses that you pay each year as a percentage of the value of your investment)

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Examples

The following examples are intended to help you compare the cost of investing in the Fund’s Institutional Shares or Institutional Plus Shares with the cost of investing in other mutual funds. They illustrate the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Fund’s shares. These examples assume that the shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense examples, reduce the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was X% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the Standard & Poor‘s 500 Index, a widely recognized benchmark of U.S. stock market performance that is dominated by the stocks of large U.S. companies. The Fund attempts to replicate the target index by investing all, or substantially all, of its assets in the stocks that make up the Index, holding each stock in approximately the same proportion as its weighting in the Index.

Principal Risks

An investment in the Fund could lose money over short or long periods of time. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• Stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling

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prices. The Fund’s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund’s target index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

• Investment style risk, which is the chance that returns from large-capitalization stocks will trail returns from the overall stock market. Large-cap stocks tend to go through cycles of doing better—or worse—than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Annual Total Returns

The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the share classes presented compare with those of the Fund‘s target index, which has investment characteristics similar to those of the Fund. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.

During the periods shown in the bar chart, the highest return for a calendar quarter was XX.XX% (quarter ended xxxx), and the lowest return for a quarter was XX.XX% (quarter ended xxxx).

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Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are shown only for the Institutional Shares and may differ for each share class. After-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.

Investment Advisor
The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Donald M. Butler, CFA, Principal of Vanguard. He has managed the Fund since 2000 (co-managed since 2016).

Michelle Louie, CFA, Portfolio Manager at Vanguard. She has co-managed the Fund since 2017.

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Purchase and Sale of Fund Shares

You may purchase or redeem shares online through our website (vanguard.com), by mail (The Vanguard Group, P.O. Box 1110, Valley Forge, PA 19482-1110), or by telephone (800-662-2739). The minimum investment amount required to open and maintain a Fund account for Institutional Shares or Institutional Plus Shares is $5 million or $100 million, respectively. The minimum investment amount required to add to an existing Fund account is generally $1. If you are investing through an employer-sponsored retirement or savings plan, your plan administrator or your benefits office can provide you with detailed information on how you can invest through your plan.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gain. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply.

Payments to Financial Intermediaries

The Fund and its investment advisor do not pay financial intermediaries for sales of Fund shares.

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Investing in Index Funds

What Is Indexing?

Indexing is an investment strategy for tracking the performance of a specified market benchmark, or “index.” An index is a group of securities whose overall performance is used as a standard to measure the investment performance of a particular market. There are many types of indexes. Some represent entire markets—such as the U.S. stock market or the U.S. bond market. Other indexes cover market segments—such as small-capitalization stocks or short-term bonds. The index sponsor determines the securities to include in the index, the weighting of each security in the index, and the appropriate time to make changes to the composition of the index. One cannot invest directly in an index.

An index fund seeks to hold all, or a representative sample, of the securities that make up its target index. Index funds attempt to mirror the performance of the target index, for better or worse. However, an index fund generally does not perform exactly like its target index. For example, index funds have operating expenses and transaction costs. Market indexes do not, and therefore they will usually have a slight performance advantage over funds that track them.

Index funds typically have the following characteristics:

• Variety of investments. Index funds generally invest in the securities of a variety of companies and industries.

• Relative performance consistency. Because they seek to track market benchmarks, index funds usually do not perform dramatically better or worse than their benchmarks.

• Low cost. Index funds are generally inexpensive to run compared with actively managed funds. They have low or no research costs and typically keep trading activity—and thus brokerage commissions and other transaction costs—to a minimum compared with actively managed funds.

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More on the Fund

This prospectus describes the principal risks you would face as a Fund shareholder. It is important to keep in mind one of the main axioms of investing: generally, the higher the risk of losing money, the higher the potential reward. The reverse, also, is generally true: the lower the risk, the lower the potential reward. As you consider an investment in any mutual fund, you should take into account your personal tolerance

for fluctuations in the securities markets. Look for this symbol throughout the prospectus. It is used to mark detailed information about the more significant risks that you would confront as a Fund shareholder. To highlight terms and concepts important to mutual fund investors, we have provided Plain Talk^® explanations along the way. Reading the prospectus will help you decide whether the Fund is the right investment for you. We suggest that you keep this prospectus for future reference.

Share Class Overview

This prospectus offers the Fund’s Institutional Shares and Institutional Plus Shares, which are generally for investors who invest a minimum of $5 million and $100 million, respectively.

Both share classes offered by the Fund have the same investment objective, strategies, and policies. However, different share classes have different expenses; as a result, their investment performances will differ.

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The following sections explain the principal investment strategies and policies that the Fund uses in pursuit of its objective. The Fund‘s board of trustees, which oversees the Fund’s management, may change investment strategies or policies in the interest of shareholders without a shareholder vote, unless those strategies or policies are designated as fundamental. Under normal circumstances, the Fund will invest at least 80% of its assets in the stocks that make up its target index. The Fund may change its 80% policy only upon 60 days‘ notice to shareholders.

Market Exposure

The Fund is subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. The Fund‘s target index tracks a subset of the U.S. stock market, which could cause the Fund to perform differently from the overall stock market. In addition, the Fund‘s target index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

To illustrate the volatility of stock prices, the following table shows the best, worst, and average annual total returns for the U.S. stock market over various periods as measured by the S&P 500 Index, a widely used barometer of U.S. stock market activity. Total returns consist of dividend income plus change in market price. Note that the returns shown do not include the costs of buying and selling stocks or other expenses that a real-world investment portfolio would incur.

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U.S. Stock Market Average Annual Returns
(1926–2017)

The table covers all of the rolling 1-, 5-, 10-, and 20-year periods from 1926 through 2017. You can see, for example, that although the average annual return on common stocks for all of the 5-year periods was XX.X%, average annual returns for individual 5-year periods ranged from XX.X% (from 1928 through 1932) to XX.X% (from 1995 through 1999). These average annual returns reflect past performance of common stocks; you should not regard them as an indication of future performance of either the stock market as a whole or the Fund in particular.

Stocks of publicly traded companies and funds that invest in stocks are often classified according to market value, or market capitalization. These classifications typically include small-cap, mid-cap, and large-cap. It is important to understand that market capitalization ranges change over time. Also, interpretations of size vary, and there are no “official” definitions of small-, mid-, and large-cap, even among Vanguard fund advisors. The asset-weighted median market capitalization of the Fund’s stock holdings as of December 31, 2017, was $X.X billion.

The Fund is subject to investment style risk, which is the chance that returns from large-capitalization stocks will trail returns from the overall stock market. Large-cap stocks tend to go through cycles of doing better—or worse—than other segments of the stock market or the stock market in general. These periods have, in the past, lasted for as long as several years.

Security Selection

The Fund attempts to track the investment performance of a benchmark index that measures the return of predominantly large-cap stocks. The Fund uses the replication method of indexing, meaning that it generally holds the same stocks as its target index, and in approximately the same proportions.

Other Investment Policies and Risks

The Fund reserves the right to substitute a different index for the index it currently tracks if the current index is discontinued, if the Fund‘s agreement with the sponsor of its target index is terminated, or for any other reason determined in good faith by

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the Fund’s board of trustees. In any such instance, the substitute index would represent the same market segment as the current index.

The Fund may invest in foreign securities to the extent necessary to carry out its investment strategy of holding all, or substantially all, of the stocks that make up the index it tracks. It is not expected that the Fund will invest more than 5% of its assets in foreign securities.

To track its target index as closely as possible, the Fund attempts to remain fully invested in stocks. To help stay fully invested and to reduce transaction costs, the Fund may invest, to a limited extent, in derivatives, including equity futures. The Fund may also use derivatives such as total return swaps to obtain exposure to a stock, a basket of stocks, or an index. Generally speaking, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, a bond, or a currency), a physical asset (such as gold, oil, or wheat), a market index (such as the S&P 500 Index), or a reference rate (such as LIBOR). Investments in derivatives may subject the Fund to risks different from, and possibly greater than, those of investments directly in the underlying securities or assets. The Fund will not use derivatives for speculation or for the purpose of leveraging (magnifying) investment returns.

Cash Management

The Fund‘s daily cash balance may be invested in one or more Vanguard CMT Funds, which are low-cost money market funds. When investing in a Vanguard CMT Fund, the Fund bears its proportionate share of the expenses of the CMT Fund in which it invests. Vanguard receives no additional revenue from Fund assets invested in a Vanguard CMT Fund.

Methods Used to Meet Redemption Requests

Under normal circumstances, the Fund typically expects to meet redemptions with other positive cash flows. When this is not an option, the Fund seeks to maintain its risk exposure by selling a cross section of the Fund’s holdings to meet redemptions, while also factoring in transaction costs. Additionally, the Fund may work with larger clients to implement their redemptions in a manner that is least disruptive to the portfolio; see “Potentially disruptive redemptions” under Redeeming Shares in the Investing With Vanguard section.

Under certain circumstances, including under stressed market conditions, there are additional tools that the Fund may use in order to meet redemptions, including advancing the settlement of market trades with counterparties to match investor redemption payments or delaying settlement of an investor’s transaction to match trade settlement within regulatory requirements. The Fund may also suspend payment of redemption proceeds for up to seven days; see “Emergency circumstances” under Redeeming Shares in the Investing With Vanguard section. Additionally under these

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unusual circumstances, the Fund may borrow money (subject to certain regulatory conditions and if available under board-approved procedures) through an interfund lending facility or through a bank line-of-credit, including a joint committed credit facility, in order to meet redemption requests.

Temporary Investment Measures

The Fund may temporarily depart from its normal investment policies and strategies when the advisor believes that doing so is in the Fund‘s best interest, so long as the strategy or policy employed is consistent with the Fund‘s investment objective. For instance, the Fund may invest beyond its normal limits in derivatives or exchange-traded funds that are consistent with the Fund‘s objective when those instruments are more favorably priced or provide needed liquidity, as might be the case when the Fund receives large cash flows that it cannot prudently invest immediately.

Frequent Trading or Market-Timing

Background. Some investors try to profit from strategies involving frequent trading of mutual fund shares, such as market-timing. For funds holding foreign securities, investors may try to take advantage of an anticipated difference between the price of the fund’s shares and price movements in overseas markets, a practice also known as time-zone arbitrage. Investors also may try to engage in frequent trading of funds holding investments such as small-cap stocks and high-yield bonds. As money is shifted into and out of a fund by a shareholder engaging in frequent trading, the fund incurs costs for buying and selling securities, resulting in increased brokerage and administrative costs. These costs are borne by all fund shareholders, including the long-term investors who do not generate the costs. In addition, frequent trading may interfere with an advisor’s ability to efficiently manage the fund.

Policies to address frequent trading. The Vanguard funds (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) do not knowingly accommodate frequent trading. The board of trustees of each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) has adopted policies and procedures reasonably designed to detect and discourage frequent trading and, in some cases, to compensate the fund for the costs associated with it. These policies and procedures do not apply to ETF Shares because frequent trading in ETF Shares generally does not disrupt portfolio management or otherwise harm fund shareholders. Although there is no assurance that Vanguard will be able to detect or prevent frequent trading or market-timing in all circumstances, the following policies have been adopted to address these issues:

• Each Vanguard fund reserves the right to reject any purchase request—including exchanges from other Vanguard funds—without notice and regardless of size. For

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example, a purchase request could be rejected because the investor has a history of frequent trading or if Vanguard determines that such purchase may negatively affect a fund’s operation or performance.

• Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) generally prohibits, except as otherwise noted in the Investing With Vanguard section, an investor’s purchases or exchanges into a fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account.

• Certain Vanguard funds charge shareholders purchase and/or redemption fees on transactions.

See the Investing With Vanguard section of this prospectus for further details on Vanguard’s transaction policies.

Each Vanguard fund (other than retail and government money market funds), in determining its net asset value, will use fair-value pricing when appropriate, as described in the Share Price section. Fair-value pricing may reduce or eliminate the profitability of certain frequent-trading strategies.

Do not invest with Vanguard if you are a market-timer.

Turnover Rate

Although the Fund generally seeks to invest for the long term, it may sell securities regardless of how long they have been held. Generally, an index fund sells securities in response to redemption requests or to changes in the composition of its target index. Turnover rates for large-cap stock index funds tend to be low because large-cap indexes—such as the S&P 500 Index—typically do not change significantly from year to year. The Financial Highlights section of this prospectus shows historical turnover rates for the Fund. A turnover rate of 100%, for example, would mean that the Fund had sold and replaced securities valued at 100% of its net assets within a one-year period.

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The Fund and Vanguard

The Fund is a member of The Vanguard Group, a family of over 200 funds holding assets of approximately $XX.X trillion. All of the funds that are members of The Vanguard Group (other than funds of funds) share in the expenses associated with administrative services and business operations, such as personnel, office space, and equipment.

Vanguard Marketing Corporation provides marketing services to the funds. Although shareholders do not pay sales commissions or 12b-1 distribution fees, each fund (other than a fund of funds) or each share class of a fund (in the case of a fund with multiple share classes) pays its allocated share of the Vanguard funds’ marketing costs.

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Investment Advisor

The Vanguard Group, Inc. (Vanguard), P.O. Box 2600, Valley Forge, PA 19482, which began operations in 1975, serves as advisor to the Fund through its Equity Index Group. As of December 31, 2017, Vanguard served as advisor for approximately $XX.X trillion in assets. Vanguard provides investment advisory services to the Fund on an at-cost basis, subject to the supervision and oversight of the trustees and officers of the Fund.

Under the terms of an SEC exemption, the Fund‘s board of trustees may, without prior approval from shareholders, change the terms of an advisory agreement with a third-party investment advisor or hire a new third-party investment advisor—either as a replacement for an existing advisor or as an additional advisor. Any significant change in the Fund’s advisory arrangements will be communicated to shareholders in

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writing. As the Fund‘s sponsor and overall manager, Vanguard may provide investment advisory services to the Fund, on an at-cost basis, at any time. Vanguard may also recommend to the board of trustees that an advisor be hired, terminated, or replaced or that the terms of an existing advisory agreement be revised. The Fund has filed an application seeking a similar SEC exemption with respect to investment advisors that are wholly owned subsidiaries of Vanguard. If granted, the Fund may rely on the new SEC relief.

The managers primarily responsible for the day-to-day management of the Fund are:

Donald M. Butler, CFA, Principal of Vanguard. He has been with Vanguard since 1992, has managed investment portfolios since 1997, and has managed the Fund since 2000 (co-managed since 2016). Education: B.S.B.A., Shippensburg University.

Michelle Louie, CFA, Portfolio Manager at Vanguard. She has been with Vanguard since 2010, has worked in investment management since 2011, has managed investment portfolios since 2016, and has co-managed the Fund since 2017. Education: B.S., The American Unviersity; M.B.A., Georgia Institute of Technology.

The Statement of Additional Information provides information about each portfolio manager’s compensation, other accounts under management, and ownership of shares of the Fund.

Dividends, Capital Gains, and Taxes

Fund Distributions

The Fund distributes to shareholders virtually all of its net income (interest and dividends, less expenses) as well as any net short-term or long-term capital gains realized from the sale of its holdings. Income dividends generally are distributed quarterly in March, June, September, and December; capital gains distributions, if any, generally occur annually in December. In addition, the Fund may occasionally make a supplemental distribution at some other time during the year.

You can receive distributions of income or capital gains in cash, or you can have them automatically reinvested in more shares of the Fund. However, if you are investing through an employer-sponsored retirement or savings plan, your distributions will be automatically reinvested in additional Fund shares.

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Basic Tax Points

Investors in taxable accounts should be aware of the following basic federal income tax points:

• Distributions are taxable to you whether or not you reinvest these amounts in additional Fund shares.

• Distributions declared in December—if paid to you by the end of January—are taxable as if received in December.

• Any dividend distribution or short-term capital gains distribution that you receive is taxable to you as ordinary income. If you are an individual and meet certain holding-period requirements with respect to your Fund shares, you may be eligible for reduced tax rates on “qualified dividend income,” if any, distributed by the Fund.

• Any distribution of net long-term capital gains is taxable to you as long-term capital gains, no matter how long you have owned shares in the Fund.

• Capital gains distributions may vary considerably from year to year as a result of the Fund‘s normal investment activities and cash flows.

• A sale or exchange of Fund shares is a taxable event. This means that you may have a capital gain to report as income, or a capital loss to report as a deduction, when you

complete your tax return.

• Any conversion between classes of shares of the same fund is a nontaxable event. By contrast, an exchange between classes of shares of different funds is a taxable event.

• Vanguard (or your intermediary) will send you a statement each year showing the tax status of all of your distributions.

Individuals, trusts, and estates whose income exceeds certain threshold amounts are subject to a 3.8% Medicare contribution tax on “net investment income.” Net investment income takes into account distributions paid by the Fund and capital gains from any sale or exchange of Fund shares.

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Dividend distributions and capital gains distributions that you receive, as well as your gains or losses from any sale or exchange of Fund shares, may be subject to state and local income taxes.

This prospectus provides general tax information only. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply. Please consult your tax advisor for detailed information about any tax consequences for you.

General Information

Backup withholding. By law, Vanguard must withhold 24% of any taxable distributions or redemptions from your account if you do not:

• Provide your correct taxpayer identification number.

• Certify that the taxpayer identification number is correct.

• Confirm that you are not subject to backup withholding.

Similarly, Vanguard (or your intermediary) must withhold taxes from your account if the IRS instructs us to do so.

Foreign investors. Vanguard funds offered for sale in the United States (Vanguard U.S. funds), including the Fund offered in this prospectus, are not widely available outside the United States. Non-U.S. investors should be aware that U.S. withholding and estate taxes and certain U.S. tax reporting requirements may apply to any investments in Vanguard U.S. funds. Foreign investors should visit the Non-U.S. Investors page on our website at vanguard.com for information on Vanguard’s non-U.S. products.

Invalid addresses. If a dividend distribution or capital gains distribution check mailed to your address of record is returned as undeliverable, Vanguard will automatically reinvest the distribution and all future distributions until you provide us with a valid

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mailing address. Reinvestments will receive the net asset value calculated on the date of the reinvestment.

Share Price

Share price, also known as net asset value (NAV), is calculated each business day as of the close of regular trading on the New York Stock Exchange (NYSE), generally 4 p.m., Eastern time. In the rare event the NYSE experiences unanticipated trade disruptions and is unavailable at the close of the trading day, NAVs will be calculated as of the close of regular trading on the Nasdaq (or another alternate exchange if the Nasdaq is unavailable, as determined at Vanguard's discretion), generally 4 p.m., Eastern time. Each share class has its own NAV, which is computed by dividing the total assets, minus liabilities, allocated to the share class by the number of Fund shares outstanding for that class. On U.S. holidays or other days when the NYSE is closed, the NAV is not calculated, and the Fund does not sell or redeem shares. However, on those days the value of the Fund’s assets may be affected to the extent that the Fund holds securities that change in value on those days (such as foreign securities that trade on foreign markets that are open).

Stocks held by a Vanguard fund are valued at their market value when reliable market quotations are readily available from the principal exchange or market on which they are traded. Such securities are generally valued at their official closing price, the last reported sales price, or if there were no sales that day, the mean between the closing bid and asking prices. When a fund determines that market quotations either are not readily available or do not accurately reflect the value of a security, the security is priced at its fair value (the amount that the owner might reasonably expect to receive upon the current sale of the security).

The values of any foreign securities held by a fund are converted into U.S. dollars using an exchange rate obtained from an independent third party as of the close of regular trading on the NYSE. The values of any mutual fund shares, including institutional money market fund shares, held by a fund are based on the NAVs of the shares. The values of any ETF shares or closed-end fund shares held by a fund are based on the market value of the shares.

A fund also will use fair-value pricing if the value of a security it holds has been materially affected by events occurring before the fund’s pricing time but after the close of the principal exchange or market on which the security is traded. This most commonly occurs with foreign securities, which may trade on foreign exchanges that close many hours before the fund’s pricing time. Intervening events might be company-specific (e.g., earnings report, merger announcement) or country-specific or regional/global (e.g., natural disaster, economic or political news, act of terrorism, interest rate change). Intervening events include price movements in U.S. markets

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that exceed a specified threshold or that are otherwise deemed to affect the value of foreign securities.

Fair-value pricing may be used for domestic securities—for example, if (1) trading in a security is halted and does not resume before the fund’s pricing time or a security does not trade in the course of a day and (2) the fund holds enough of the security that its price could affect the NAV.

Fair-value prices are determined by Vanguard according to procedures adopted by the board of trustees. When fair-value pricing is employed, the prices of securities used by a fund to calculate the NAV may differ from quoted or published prices for the same securities.

Vanguard fund share prices are published daily on our website at vanguard.com/prices.

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Financial Highlights

The following financial highlights tables are intended to help you understand the Fund’s financial performance for the periods shown, and certain information reflects financial results for a single Fund share. The total returns in each table represent the rate that an investor would have earned or lost each period on an investment in the Fund (assuming reinvestment of all distributions). This information has been obtained from the financial statements audited by *, an independent registered public accounting firm, whose report—along with the Fund’s financial statements—is included in the Fund‘s most recent annual report to shareholders. You may obtain a free copy of the latest annual or semiannual report by visiting vanguard.com or by contacting Vanguard by telephone or mail.

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1 Net investment income per share and the ratio of net investment income to average net assets include $0.677 and 0.36%, respectively, resulting from income received from Medtronic plc in January 2015.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares.

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1 Net investment income per share and the ratio of net investment income to average net assets include $0.677 and 0.36%, respectively, resulting from income received from Medtronic plc in January 2015.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares.

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Investing With Vanguard

This section of the prospectus explains the basics of doing business with Vanguard. Vanguard fund shares can be held directly with Vanguard or indirectly through an intermediary, such as a bank, a broker, or an investment advisor. If you hold Vanguard fund shares directly with Vanguard, you should carefully read each topic within this section that pertains to your relationship with Vanguard. If you hold Vanguard fund shares indirectly through an intermediary (including shares held through a Vanguard brokerage account), please see Investing With Vanguard Through Other Firms, and also refer to your account agreement with the intermediary for information about transacting in that account. If you hold Vanguard fund shares through an employer-sponsored retirement or savings plan, please see Employer-Sponsored Plans. Vanguard reserves the right to change the following policies without notice. Please call or check online for current information. See Contacting Vanguard.

For Vanguard fund shares held directly with Vanguard, each fund you hold in an account is a separate “fund account.” For example, if you hold three funds in a nonretirement account titled in your own name, two funds in a nonretirement account titled jointly with your spouse, and one fund in an individual retirement account, you have six fund accounts—and this is true even if you hold the same fund in multiple accounts. Note that each reference to “you” in this prospectus applies to any one or more registered account owners or persons authorized to transact on your account.

Purchasing Shares

Vanguard reserves the right, without notice, to increase or decrease the minimum amount required to open, convert shares to, or maintain a fund account or to add to an existing fund account.

Investment minimums may differ for certain categories of investors.

Account Minimums for Institutional Shares and Institutional Plus Shares To open and maintain an account. Institutional Shares—$5 million; Institutional Plus Shares—$100 million. If you request Institutional Plus Shares when you open a new account but the investment amount does not meet the account minimum for Institutional Plus shares, your investment will be placed in Institutional Shares of the Fund. Institutional clients should contact Vanguard for information on special eligibility rules that may apply to them.

Certain Vanguard institutional clients may meet the minimum investment amount by aggregating separate accounts within the same Fund. This aggregation policy does not apply to financial intermediaries.

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Vanguard may charge additional recordkeeping fees for institutional clients whose accounts are recordkept by Vanguard. Please contact your Vanguard representative to determine whether additional recordkeeping fees apply to your account.

To add to an existing account. Generally $1.

How to Initiate a Purchase Request

Be sure to check Exchanging Shares, Frequent-Trading Limitations, and Other Rules You Should Know before placing your purchase request.

Online. You may open certain types of accounts, request a purchase of shares, and request an exchange through our website or our mobile application if you are registered for online access.

By telephone. You may call Vanguard to begin the account registration process or request that the account-opening forms be sent to you. You may also call Vanguard to request a purchase of shares in your account or to request an exchange. See

Contacting Vanguard.

By mail. You may send Vanguard your account registration form and check to open a new fund account. To add to an existing fund account, you may send your check with an Invest-by-Mail form (from a transaction confirmation or your account statement), with a deposit slip (available online), or with a written request. You may also send a written request to Vanguard to make an exchange. For a list of Vanguard addresses, see Contacting Vanguard.

How to Pay for a Purchase

By electronic bank transfer. You may purchase shares of a Vanguard fund through an electronic transfer of money from a bank account. To establish the electronic bank transfer service on an account, you must designate the bank account online, complete a special form, or fill out the appropriate section of your account registration form. After the service is set up on your account, you can purchase shares by electronic bank transfer on a regular schedule (Automatic Investment Plan) or upon request. Your purchase request can be initiated online (if you are registered for online access), by telephone, or by mail.

By wire. Wiring instructions vary for different types of purchases. Please call Vanguard for instructions and policies on purchasing shares by wire. See Contacting Vanguard.

By check. You may make initial or additional purchases to your fund account by sending a check or by utilizing our mobile application if you are registered for online access. Also see How to Initiate a Purchase Request. Make your check payable to Vanguard and include the appropriate fund number (e.g., Vanguard—xx). For a list of Fund numbers (for share classes in this prospectus), see Additional Information.

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By exchange. You may purchase shares of a Vanguard fund using the proceeds from the simultaneous redemption of shares of another Vanguard fund. You may initiate an exchange online (if you are registered for online access), by telephone, or by mail. See

Exchanging Shares.

Trade Date

The trade date for any purchase request received in good order will depend on the day and time Vanguard receives your request, the manner in which you are paying, and the type of fund you are purchasing. Your purchase will be executed using the net asset value (NAV) as calculated on the trade date. NAVs are calculated only on days that the New York Stock Exchange (NYSE) is open for trading (a business day).

For purchases by check into all funds other than money market funds and for purchases by exchange, wire, or electronic bank transfer (not using an Automatic Investment Plan) into all funds: If the purchase request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date for the purchase will be the same day. If the purchase request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date for the purchase will be the next business day.

For purchases by check into money market funds: If the purchase request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date for the purchase will be the next business day. If the purchase request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date for the purchase will be the second business day following the day Vanguard receives the purchase request. Because money market instruments must be purchased with federal funds and it takes a money market mutual fund one business day to convert check proceeds into federal funds, the trade date for the purchase will be one business day later than for other funds.

For purchases by electronic bank transfer using an Automatic Investment Plan: Your trade date generally will be the date you selected for withdrawal of funds from your designated bank account. Your bank account generally will be debited on the business day after your trade date. If the date you selected for withdrawal of funds from your bank account falls on a weekend, holiday, or other nonbusiness day, your trade date generally will be the previous business day. For retirement accounts, if the date you selected for withdrawal of funds from your designated bank account falls on the last business day of the year, your trade date will be the first business day of the following year. Please note that if you select the first of the month for automated withdrawals from your designated bank account, trades designated for January 1 will receive the next business day’s trade date.

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If your purchase request is not accurate and complete, it may be rejected. See Other Rules You Should Know—Good Order.

For further information about purchase transactions, consult our website at vanguard.com or see Contacting Vanguard.

Other Purchase Rules You Should Know

Check purchases. All purchase checks must be written in U.S. dollars and must be drawn on a U.S. bank. Vanguard does not accept cash, traveler’s checks, starter checks, or money orders. In addition, Vanguard may refuse checks that are not made payable to Vanguard.

New accounts. We are required by law to obtain from you certain personal information that we will use to verify your identity. If you do not provide the information, we may not be able to open your account. If we are unable to verify your identity, Vanguard reserves the right, without notice, to close your account or take such other steps as we deem reasonable. Certain types of accounts may require additional documentation.

Refused or rejected purchase requests. Vanguard reserves the right to stop selling fund shares or to reject any purchase request at any time and without notice, including, but not limited to, purchases requested by exchange from another Vanguard fund. This also includes the right to reject any purchase request because the investor has a history of frequent trading or because the purchase may negatively affect a fund’s operation or performance.

Large purchases. Call Vanguard before attempting to invest a large dollar amount.

No cancellations. Vanguard will not accept your request to cancel any purchase request once processing has begun. Please be careful when placing a purchase request.

Converting Shares

When a conversion occurs, you receive shares of one class in place of shares of another class of the same fund. At the time of conversion, the dollar value of the “new” shares you receive equals the dollar value of the “old” shares that were converted. In other words, the conversion has no effect on the value of your investment in the fund at the time of the conversion. However, the number of shares you own after the conversion may be greater than or less than the number of shares you owned before the conversion, depending on the NAVs of the two share classes.

Vanguard will not accept your request to cancel any self-directed conversion request once processing has begun. Please be careful when placing a conversion request.

A conversion between share classes of the same fund is a nontaxable event.

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Trade Date

The trade date for any conversion request received in good order will depend on the day and time Vanguard receives your request. Your conversion will be executed using the NAVs of the different share classes on the trade date. NAVs are calculated only on days that the NYSE is open for trading (a business day).

For a conversion request received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. For a conversion request received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day. See Other Rules You Should Know.

Conversions From Institutional Shares to Institutional Plus Shares

You may convert Institutional Shares to Institutional Plus Shares of the Fund, provided that your account balance is at least $100 million.

Mandatory Conversions to Institutional Shares

If an account no longer meets the balance requirements for Institutional Plus Shares, Vanguard may automatically convert the shares in the account to Institutional Shares. A decline in the account balance because of market movement may result in such a conversion. Vanguard will notify the investor in writing before any mandatory conversion occurs.

Redeeming Shares

How to Initiate a Redemption Request

Be sure to check Exchanging Shares, Frequent-Trading Limitations, and Other Rules You Should Know before placing your redemption request.

Online. You may request a redemption of shares or request an exchange through our website or our mobile application if you are registered for online access.

By telephone. You may call Vanguard to request a redemption of shares or an exchange. See Contacting Vanguard.

By mail. You may send a written request to Vanguard to redeem from a fund account or to make an exchange. See Contacting Vanguard.

How to Receive Redemption Proceeds

By electronic bank transfer. You may have the proceeds of a fund redemption sent directly to a designated bank account. To establish the electronic bank transfer service on an account, you must designate a bank account online, complete a special form, or fill out the appropriate section of your account registration form. After the service is set

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up on your account, you can redeem shares by electronic bank transfer on a regular schedule (Automatic Withdrawal Plan) or upon request. Your redemption request can be initiated online (if you are registered for online access), by telephone, or by mail.

By wire. To receive your proceeds by wire, you may instruct Vanguard to wire your redemption proceeds ($100 minimum) to a previously designated bank account. To establish the wire redemption service, you generally must designate a bank account online, complete a special form, or fill out the appropriate section of your account registration form.

Please note that Vanguard charges a $10 wire fee for outgoing wire redemptions. The fee is assessed in addition to, rather than being withheld from, redemption proceeds and is paid directly to the fund. For example, if you redeem $100 via a wire, you will receive the full $100, and your fund account will also be assessed the $10 fee by redeeming additional fund shares. If you redeem your entire fund account, your redemption proceeds will be reduced by the fee amount. The wire fee does not apply to accounts held by Flagship and Flagship Select clients; accounts held through intermediaries, including Vanguard Brokerage Services; or accounts held by institutional clients.

By exchange. You may have the proceeds of a Vanguard fund redemption invested directly in shares of another Vanguard fund. You may initiate an exchange online (if you are registered for online access), by telephone, or by mail. See Exchanging Shares.

By check. If you have not chosen another redemption method, Vanguard will mail you a redemption check, generally payable to all registered account owners, normally within two business days of your trade date, and generally to the address of record.

Trade Date

The trade date for any redemption request received in good order will depend on the day and time Vanguard receives your request and the manner in which you are redeeming. Your redemption will be executed using the NAV as calculated on the trade date. NAVs are calculated only on days that the NYSE is open for trading (a business day).

For redemptions by check, exchange, or wire: If the redemption request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. If the redemption request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day.

• Note on timing of wire redemptions from money market funds: For telephone requests received by Vanguard on a business day before 10:45 a.m., Eastern time (2 p.m., Eastern time, for Vanguard Prime Money Market Fund; 12:30 p.m., Eastern time, for Vanguard Federal Money Market Fund), the redemption proceeds

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generally will leave Vanguard by the close of business the same day. For telephone requests received by Vanguard on a business day after those cut-off times, or on a nonbusiness day, and for all requests other than by telephone, the redemption proceeds generally will leave Vanguard by the close of business on the next business day.

• Note on timing of wire redemptions from all other funds: For requests received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the redemption proceeds generally will leave Vanguard by the close of business on the next business day. For requests received by Vanguard on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the redemption proceeds generally will leave Vanguard by the close of business on the second business day after Vanguard receives the request.

For redemptions by electronic bank transfer using an Automatic Withdrawal Plan: Your trade date generally will be the date you selected for withdrawal of funds (redemption of shares) from your Vanguard account. Proceeds of redeemed shares generally will be credited to your designated bank account two business days after your trade date. If the date you selected for withdrawal of funds from your Vanguard account falls on a weekend, holiday, or other nonbusiness day, your trade date generally will be the previous business day. For retirement accounts, if the date you selected for withdrawal of funds from your Vanguard account falls on the last day of the year and if that date is a holiday, your trade date will be the first business day of the following year. Please note that if you designate the first of the month for automated withdrawals, trades designated for January 1 will receive the next business day’s trade date.

For redemptions by electronic bank transfer not using an Automatic Withdrawal Plan: If the redemption request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. If the redemption request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day.

If your redemption request is not accurate and complete, it may be rejected. If we are unable to send your redemption proceeds by wire or electronic bank transfer because the receiving institution rejects the transfer, Vanguard will make additional efforts to complete your transaction. If Vanguard is still unable to complete the transaction, we may send the proceeds of the redemption to you by check, generally payable to all registered account owners, or use your proceeds to purchase new shares of the fund from which you sold shares for the purpose of the wire or electronic bank transfer transaction. See Other Rules You Should Know—Good Order.

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If your redemption request is received in good order, we typically expect that redemption proceeds will be paid by the Fund within one business day of the trade date; however, in certain circumstances, investors may experience a longer settlement period at the time of the transaction. For further information, see “Potentially disruptive redemptions” and “Emergency circumstances.”

For further information about redemption transactions, consult our website at vanguard.com or see Contacting Vanguard.

Other Redemption Rules You Should Know

Documentation for certain accounts. Special documentation may be required to redeem from certain types of accounts, such as trust, corporate, nonprofit, or retirement accounts. Please call us before attempting to redeem from these types of accounts.

Potentially disruptive redemptions. Vanguard reserves the right to pay all or part of a redemption in kind—that is, in the form of securities—if we reasonably believe that a cash redemption would negatively affect the fund’s operation or performance or that the shareholder may be engaged in market-timing or frequent trading. Under these circumstances, Vanguard also reserves the right to delay payment of the redemption proceeds for up to seven calendar days. By calling us before you attempt to redeem a large dollar amount, you may avoid in-kind or delayed payment of your redemption. Please see Frequent-Trading Limitations for information about Vanguard’s policies to limit frequent trading.

Recently purchased shares. Although you can redeem shares at any time, proceeds may not be made available to you until the fund collects payment for your purchase. This may take up to seven calendar days for shares purchased by check or by electronic bank transfer. If you have written a check on a fund with checkwriting privileges, that check may be rejected if your fund account does not have a sufficient available balance.

Share certificates. Share certificates are no longer issued for Vanguard funds. Shares currently held in certificates cannot be redeemed, exchanged, converted, or transferred (reregistered) until you return the certificates (unsigned) to Vanguard by registered mail. For the correct address, see Contacting Vanguard.

Address change. If you change your address online or by telephone, there may be up to a 15-day restriction on your ability to request check redemptions online and by telephone. You can request a redemption in writing at any time. Confirmations of address changes are sent to both the old and new addresses.

Payment to a different person or address. At your request, we can make your redemption check payable, or wire your redemption proceeds, to a different person or send it to a different address. However, this generally requires the written consent of

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all registered account owners and may require additional documentation, such as a signature guarantee or a notarized signature. You may obtain a signature guarantee from some commercial or savings banks, credit unions, trust companies, or member firms of a U.S. stock exchange.

No cancellations. Vanguard will not accept your request to cancel any redemption request once processing has begun. Please be careful when placing a redemption request.

Emergency circumstances. Vanguard funds can postpone payment of redemption proceeds for up to seven calendar days. In addition, Vanguard funds can suspend redemptions and/or postpone payments of redemption proceeds beyond seven calendar days at times when the NYSE is closed or during emergency circumstances, as determined by the SEC.

Exchanging Shares

An exchange occurs when you use the proceeds from the redemption of shares of one Vanguard fund to simultaneously purchase shares of a different Vanguard fund. You can make exchange requests online (if you are registered for online access), by telephone, or by mail. See Purchasing Shares and Redeeming Shares.

If the NYSE is open for regular trading (generally until 4 p.m., Eastern time, on a business day) at the time an exchange request is received in good order, the trade date generally will be the same day. See Other Rules You Should Know—Good Order for additional information on all transaction requests.

Vanguard will not accept your request to cancel any exchange request once processing has begun. Please be careful when placing an exchange request.

Call Vanguard before attempting to exchange a large dollar amount. By calling us before you attempt to exchange a large dollar amount, you may avoid delayed or rejected transactions.

Please note that Vanguard reserves the right, without notice, to revise or terminate the exchange privilege, limit the amount of any exchange, or reject an exchange, at any time, for any reason. See Frequent-Trading Limitations for additional restrictions on exchanges.

Frequent-Trading Limitations

Because excessive transactions can disrupt management of a fund and increase the fund’s costs for all shareholders, the board of trustees of each Vanguard fund places certain limits on frequent trading in the funds. Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) limits an investor’s purchases or exchanges into a

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fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account. ETF Shares are not subject to these frequent-trading limits.

For Vanguard Retirement Investment Program pooled plans, the limitations apply to exchanges made online or by telephone.

These frequent-trading limitations do not apply to the following:

• Purchases of shares with reinvested dividend or capital gains distributions.

• Transactions through Vanguard’s Automatic Investment Plan, Automatic Exchange Service, Direct Deposit Service, Automatic Withdrawal Plan, Required Minimum Distribution Service, and Vanguard Small Business Online^®.

• Discretionary transactions through Vanguard Asset Management Services^™, Vanguard Personal Advisor Services^®, and Vanguard Institutional Advisory Services^®.

• Redemptions of shares to pay fund or account fees.

• Redemptions of shares to remove excess shareholder contributions to certain types of retirement accounts (including, but not limited to, IRAs, certain Individual 403(b)(7) Custodial Accounts, and Vanguard Individual 401(k) Plans).

• Transfers and reregistrations of shares within the same fund.

• Purchases of shares by asset transfer or direct rollover.

• Conversions of shares from one share class to another in the same fund.

• Checkwriting redemptions.

• Section 529 college savings plans.

• Certain approved institutional portfolios and asset allocation programs, as well as trades made by funds or trusts managed by Vanguard or its affiliates that invest in other Vanguard funds. (Please note that shareholders of Vanguard’s funds of funds are subject to the limitations.)

For participants in employer-sponsored defined contribution plans,* the frequent-trading limitations do not apply to:

• Purchases of shares with participant payroll or employer contributions or loan repayments.

• Purchases of shares with reinvested dividend or capital gains distributions.

• Distributions, loans, and in-service withdrawals from a plan.

• Redemptions of shares as part of a plan termination or at the direction of the plan.

• Transactions executed through the Vanguard Managed Account Program.

• Redemptions of shares to pay fund or account fees.

• Share or asset transfers or rollovers.

• Reregistrations of shares.

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• Conversions of shares from one share class to another in the same fund.

• Exchange requests submitted by written request to Vanguard. (Exchange requests

submitted by fax, if otherwise permitted, are subject to the limitations.)

* The following Vanguard fund accounts are subject to the frequent-trading limitations: SEP-IRAs, SIMPLE IRAs, certain Individual 403(b)(7) Custodial Accounts, and Vanguard Individual 401(k) Plans.

Accounts Held by Institutions (Other Than Defined Contribution Plans)

Vanguard will systematically monitor for frequent trading in institutional clients’ accounts. If we detect suspicious trading activity, we will investigate and take appropriate action, which may include applying to a client’s accounts the 30-day policy previously described, prohibiting a client’s purchases of fund shares, and/or revoking the client’s exchange privilege.

Accounts Held by Intermediaries

When intermediaries establish accounts in Vanguard funds for the benefit of their clients, we cannot always monitor the trading activity of the individual clients. However, we review trading activity at the intermediary (omnibus) level, and if we detect suspicious activity, we will investigate and take appropriate action. If necessary, Vanguard may prohibit additional purchases of fund shares by an intermediary, including for the benefit of certain of the intermediary’s clients. Intermediaries also may monitor their clients’ trading activities with respect to Vanguard funds.

For those Vanguard funds that charge purchase and/or redemption fees, intermediaries will be asked to assess these fees on client accounts and remit these fees to the funds. The application of purchase and redemption fees and frequent-trading limitations may vary among intermediaries. There are no assurances that Vanguard will successfully identify all intermediaries or that intermediaries will properly assess purchase and redemption fees or administer frequent-trading limitations. If you invest with Vanguard through an intermediary, please read that firm’s materials carefully to learn of any other rules or fees that may apply.

Other Rules You Should Know

Prospectus and Shareholder Report Mailings

When two or more shareholders have the same last name and address, just one summary prospectus (or prospectus) and/or shareholder report may be sent in an attempt to eliminate the unnecessary expense of duplicate mailings. You may request

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individual prospectuses and reports by contacting our Client Services Department in writing, by telephone, or online. See Contacting Vanguard.

Vanguard.com

Registration. If you are a registered user of vanguard.com, you can review your account holdings; buy, sell, or exchange shares of most Vanguard funds; and perform most other transactions through our website. You must register for this service online.

Electronic delivery. Vanguard can deliver your account statements, transaction confirmations, prospectuses, certain tax forms, and shareholder reports electronically. If you are a registered user of vanguard.com, you can consent to the electronic delivery of these documents by logging on and changing your mailing preferences under “Account Maintenance.” You can revoke your electronic consent at any time through our website, and we will begin to send paper copies of these documents within 30 days of receiving your revocation.

Telephone Transactions

Automatic. When we set up your account, we will automatically enable you to do business with us by telephone, unless you instruct us otherwise in writing.

Tele-Account^®. To obtain fund and account information through Vanguard’s automated telephone service, you must first establish a Personal Identification Number (PIN) by calling Tele-Account at 800-662-6273.

Proof of a caller’s authority. We reserve the right to refuse a telephone request if the caller is unable to provide the requested information or if we reasonably believe that the caller is not an individual authorized to act on the account. Before we allow a caller to act on an account, we may request the following information:

• Authorization to act on the account (as the account owner or by legal documentation or other means).

• Account registration and address.

• Fund name and account number, if applicable.

• Other information relating to the caller, the account owner, or the account.

Good Order

We reserve the right to reject any transaction instructions that are not in “good order.” Good order generally means that your instructions:

• Are provided by the person(s) authorized in accordance with Vanguard’s policies and procedures to access the account and request transactions.

• Include the fund name and account number.

• Include the amount of the transaction (stated in dollars, shares, or percentage).

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Written instructions also must generally include:

• An original signature and date from the authorized person(s).

• Signature guarantees or notarized signatures, if required for the type of transaction.

(Call Vanguard for specific requirements.)

• Any supporting documentation that may be required.

Written instructions may be acceptable when a Vanguard form is not applicable. The requirements vary among types of accounts and transactions. For more information, consult our website at vanguard.com or see Contacting Vanguard.

Vanguard reserves the right, without notice, to revise the requirements for good order.

Future Trade-Date Requests

Vanguard does not accept requests to hold a purchase, conversion, redemption, or exchange transaction for a future date. All such requests will receive trade dates as previously described in Purchasing Shares, Converting Shares, Redeeming Shares, and

Exchanging Shares. Vanguard reserves the right to return future-dated purchase checks.

Accounts With More Than One Owner

If an account has more than one owner or authorized person, Vanguard generally will accept instructions from any one owner or authorized person.

Responsibility for Fraud

Vanguard will not be responsible for any account losses because of fraud if we reasonably believe that the person transacting business on an account is authorized to do so. Please take precautions to protect yourself from fraud. Keep your account information private, and immediately review any account statements or other information that we provide to you. It is important that you contact Vanguard immediately about any transactions or changes to your account that you believe to be unauthorized.

Uncashed Checks

Please cash your distribution or redemption checks promptly. Vanguard will not pay interest on uncashed checks. Vanguard may be required to transfer assets related to uncashed checks to a state under the state’s abandoned property law.

Dormant Accounts

If your account has no activity in it for a period of time, Vanguard may be required to transfer it to a state under the state’s abandoned property law.

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Unusual Circumstances

If you experience difficulty contacting Vanguard online or by telephone, you can send us your transaction request by regular or express mail. See Contacting Vanguard for addresses.

Investing With Vanguard Through Other Firms

You may purchase or sell shares of most Vanguard funds through a financial intermediary, such as a bank, a broker, or an investment advisor. Please consult your financial intermediary to determine which, if any, shares are available through that firm and to learn about other rules that may apply. Your financial intermediary can provide you with account information and any required tax forms.

Please see Frequent-Trading Limitations—Accounts Held by Intermediaries for information about the assessment of any purchase or redemption fees and the monitoring of frequent trading for accounts held by intermediaries.

Low-Balance Accounts

The Fund reserves the right to convert an investor’s Institutional Plus Shares to Institutional Shares of the Fund if the investor’s fund account balance falls below the account minimum for any reason, including market fluctuation. In addition, the Fund reserves the right to liquidate an investor’s Institutional Shares if the investor’s fund account balance falls below the account minimum for that share class for any reason, including market fluctuation. This liquidation policy applies to nonretirement fund accounts and accounts that are held through intermediaries. Any such conversion or liquidation will be preceded by written notice to the investor.

Right to Change Policies

In addition to the rights expressly stated elsewhere in this prospectus, Vanguard reserves the right, without notice, to (1) alter, add, or discontinue any conditions of purchase (including eligibility requirements), redemption, exchange, conversion, service, or privilege at any time; (2) accept initial purchases by telephone; (3) freeze any account and/or suspend account services if Vanguard has received reasonable notice of a dispute regarding the assets in an account, including notice of a dispute between the registered or beneficial account owners, or if Vanguard reasonably believes a fraudulent transaction may occur or has occurred; (4) temporarily freeze any account and/or suspend account services upon initial notification to Vanguard of the death of the shareholder until Vanguard receives required documentation in good order; (5) alter, impose, discontinue, or waive any purchase fee, redemption fee, account service fee, or other fees charged to a shareholder or a group of shareholders; and (6) redeem an account or suspend account privileges, without the owner’s permission to do so, in cases of threatening conduct or activity Vanguard believes to be suspicious, fraudulent, or illegal. Changes may affect any or all investors. These actions will be taken when, at

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the sole discretion of Vanguard management, Vanguard reasonably believes they are in the best interest of a fund.

Share Classes

Vanguard reserves the right, without notice, to change the eligibility requirements of its share classes, including the types of clients who are eligible to purchase each share class.

Fund and Account Updates

Confirmation Statements

We will send (or provide through our website, whichever you prefer) a confirmation of your trade date and the amount of your transaction when you buy, sell, exchange, or convert shares. However, we will not send confirmations reflecting only checkwriting redemptions or the reinvestment of dividend or capital gains distributions. For any month in which you had a checkwriting redemption, a Checkwriting Activity Statement will be sent to you itemizing the checkwriting redemptions for that month. Promptly review each confirmation statement that we provide to you. It is important that you contact Vanguard immediately with any questions you may have about any transaction reflected on a confirmation statement, or Vanguard will consider the transaction properly processed.

Portfolio Summaries

We will send (or provide through our website, whichever you prefer) quarterly portfolio summaries to help you keep track of your accounts throughout the year. If you prefer, you may request to receive monthly portfolio summaries. Each summary shows the market value of your account at the close of the statement period, as well as all distributions, purchases, redemptions, exchanges, transfers, and conversions for the current calendar quarter (or month). Promptly review each summary that we provide to you. It is important that you contact Vanguard immediately with any questions you may have about any transaction reflected on the summary, or Vanguard will consider the transaction properly processed.

Tax Information Statements

For most accounts, Vanguard (or your intermediary) is required to provide annual tax forms to assist you in preparing your income tax returns. These forms are generally available for each calendar year early in the following year. Registered users of vanguard.com can also view certain forms through our website. Vanguard (or your intermediary) may also provide you with additional tax-related documentation. For more information, consult our website at vanguard.com or see Contacting Vanguard.

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Annual and Semiannual Reports

We will send (or provide through our website, whichever you prefer) reports about Vanguard Institutional Index Fund twice a year, in February and August. These reports include overviews of the financial markets and provide the following specific Fund information:

• Performance assessments and comparisons with industry benchmarks.
• Financial statements with listings of Fund holdings.

Portfolio Holdings

Please consult the Fund‘s Statement of Additional Information or our website for a description of the policies and procedures that govern disclosure of the Fund’s portfolio holdings.

Employer-Sponsored Plans

Your plan administrator or your employee benefits office can provide you with detailed information on how to participate in your plan and how to elect the Fund as an investment option.

• If you have any questions about the Fund or Vanguard, including those about the Fund’s investment objective, strategies, or risks, contact Vanguard Participant Services toll-free at 800-523-1188 or visit our website at vanguard.com.

• If you have questions about your account, contact your plan administrator or the organization that provides recordkeeping services for your plan.

• Be sure to carefully read each topic that pertains to your transactions with Vanguard.

Vanguard reserves the right to change its policies without notice to shareholders.

Transactions

Processing times for your transaction requests may differ among recordkeepers or among transaction and funding types. Your plan’s recordkeeper (which may also be Vanguard) will determine the necessary processing time frames for your transaction requests prior to submission to the Fund. Consult your recordkeeper or plan administrator for more information.

If Vanguard is serving as your plan recordkeeper and if your transaction involves one or more investments with an early cut-off time for processing or another trading restriction, your entire transaction will be subject to the restriction when the trade date for your transaction is determined.

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Vanguard Addresses

Please be sure to use the correct address. Use of an incorrect address could delay the processing of your transaction.

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CFA^® is a registered trademark owned by CFA Institute.

The "S&P 500 Index" (the “Index”) is a product of S&P Dow Jones Indices LLC (“SPDJI”), and has been licensed for use by Vanguard. Standard & Poor’s® and S&P® are registered trademarks of Standard & Poor’s Financial Services LLC (“S&P”); Dow Jones® is a registered trademark of Dow Jones Trademark Holdings LLC (“Dow Jones”); S&P® and S&P 500® are trademarks of S&P; and these trademarks have been licensed for use by SPDJI and sublicensed for certain purposes by Vanguard. Vanguard Institutional Index Fund is not sponsored, endorsed, sold or promoted by SPDJI, Dow Jones, S&P, any of their respective affiliates (collectively, “S&P Dow Jones Indices”). S&P Dow Jones Indices make no representation or warranty, express or implied, to the owners of the Institutional Index Fund or any member of the public regarding the advisability of investing in securities generally or in Vanguard Institutional Index Fund particularly or the ability of the S&P 500 Index to track general market performance. S&P Dow Jones Indices’ only relationship to Vanguard with respect to the S&P 500 Index is the licensing of the Index and certain trademarks, service marks and/or trade names of S&P Dow Jones Indices and/or its licensors. The S&P 500 Index is determined, composed and calculated by S&P Dow Jones Indices without regard to Vanguard or the Institutional Index Fund. S&P Dow Jones Indices have no obligation to take the needs of Vanguard or the owners of Vanguard Institutional Index Fund into consideration in determining, composing or calculating the S&P 500 Index. S&P Dow Jones Indices are not responsible for and have not participated in the determination of the prices, and amount of Vanguard Institutional Index Fund or the timing of the issuance or sale of Vanguard Institutional Index Fund or in the determination or calculation of the equation by which Vanguard Institutional Index Fund is to be converted into cash, surrendered or redeemed, as the case may be. S&P Dow Jones Indices have no obligation or liability in connection with the administration, marketing or trading of Vanguard Institutional Index Fund. There is no assurance that investment products based on the S&P 500 Index will accurately track index performance or provide positive investment returns. S&P Dow Jones Indices LLC is not an investment advisor. Inclusion of a security within an index is not a recommendation by S&P Dow Jones Indices to buy, sell, or hold such security, nor is it considered to be investment advice.

S&P DOW JONES INDICES DOES NOT GUARANTEE THE ADEQUACY, ACCURACY, TIMELINESS AND/OR THE COMPLETENESS OF THE INDEX OR ANY DATA RELATED THERETO OR ANY COMMUNICATION, INCLUDING BUT NOT LIMITED TO, ORAL OR WRITTEN COMMUNICATION (INCLUDING ELECTRONIC COMMUNICATIONS) WITH RESPECT THERETO. S&P DOW JONES INDICES SHALL NOT BE SUBJECT TO ANY DAMAGES OR LIABILITY FOR ANY ERRORS, OMISSIONS, OR DELAYS THEREIN. S&P DOW JONES INDICES MAKE NO EXPRESS OR IMPLIED WARRANTIES, AND EXPRESSLY DISCLAIMS ALL WARRANTIES, OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE OR AS TO RESULTS TO BE OBTAINED BY VANGUARD, OWNERS OF VANGUARD INSTITUTIONAL INDEX FUND, OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE INDEX OR WITH RESPECT TO ANY DATA RELATED THERETO. WITHOUT LIMITING ANY OF THE FOREGOING, IN NO EVENT WHATSOEVER SHALL S&P DOW JONES INDICES BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO, LOSS OF PROFITS, TRADING LOSSES, LOST TIME OR GOODWILL, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES, WHETHER IN CONTRACT, TORT, STRICT LIABILITY, OR OTHERWISE. THERE ARE NO THIRD PARTY BENEFICIARIES OF ANY AGREEMENTS OR ARRANGEMENTS BETWEEN S&P DOW JONES INDICES AND VANGUARD, OTHER THAN THE LICENSORS OF S&P DOW JONES INDICES.

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Glossary of Investment Terms

Active Management. An investment approach that seeks to exceed the average returns of a particular financial market or market segment. In selecting securities to buy and sell, active managers may rely on, among other things, research, market forecasts, quantitative models, and their own judgment and experience.

Capital Gains Distribution. Payment to mutual fund shareholders of gains realized on securities that a fund has sold at a profit, minus any realized losses.

Common Stock. A security representing ownership rights in a corporation.

Dividend Distribution. Payment to mutual fund shareholders of income from interest or dividends generated by a fund’s investments.

Expense Ratio. A fund’s total annual operating expenses expressed as a percentage of the fund’s average net assets. The expense ratio includes management and administrative expenses, but it does not include the transaction costs of buying and selling portfolio securities.

Inception Date. The date on which the assets of a fund (or one of its share classes) are first invested in accordance with the fund’s investment objective. For funds with a subscription period, the inception date is the day after that period ends. Investment performance is generally measured from the inception date.

Indexing. A low-cost investment strategy in which a mutual fund attempts to track—rather than outperform—a specified market benchmark, or “index.”

Joint Committed Credit Facility. The Fund participates, along with other funds managed by Vanguard, in a committed credit facility provided by a syndicate of lenders pursuant to a credit agreement that may be renewed annually; each fund is individually liable for its borrowings, if any, under the credit facility. The amount and terms of the committed credit facility are subject to approval by the fund’s board of trustees and renegotiation with the lender syndicate on an annual basis.

Median Market Capitalization. An indicator of the size of companies in which a fund invests; the midpoint of market capitalization (market price x shares outstanding) of a fund’s stocks, weighted by the proportion of the fund’s assets invested in each stock. Stocks representing half of the fund’s assets have market capitalizations above the median, and the rest are below it.

Mutual Fund. An investment company that pools the money of many people and invests it in a variety of securities in an effort to achieve a specific objective over time.

New York Stock Exchange (NYSE). A stock exchange based in New York City that is open for regular trading on business days, Monday through Friday, from 9:30 a.m. to 4 p.m., Eastern time. Net asset values (NAVs) are calculated each business day as of the close of regular trading on the NYSE.

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Securities. Stocks, bonds, money market instruments, and other investments.

Total Return. A percentage change, over a specified time period, in a mutual fund’s net asset value, assuming the reinvestment of all distributions of dividends and capital gains.

Volatility. The fluctuations in value of a mutual fund or other security. The greater a fund’s volatility, the wider the fluctuations in its returns.

Yield. Income (interest or dividends) earned by an investment, expressed as a percentage of the investment’s price.

Institutional Division P.O. Box 2900 Valley Forge, PA 19482-2900

Connect with Vanguard^® > vanguard.com

For More Information

If you would like more information about Vanguard Institutional Index Fund, the following documents are available free upon request:

Annual/Semiannual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semiannual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Statement of Additional Information (SAI)

The SAI provides more detailed information about the Fund and is incorporated by reference into (and thus legally a part of) this prospectus.

To receive a free copy of the latest annual or semiannual report or the SAI, or to request additional information about the Fund or other Vanguard funds, please visit vanguard.com or contact us as follows:

If you are an individual investor:

The Vanguard Group

Investor Information Department P.O. Box 2900 Valley Forge, PA 19482-2900

Telephone: 800-662-7447; Text telephone for people with hearing impairment: 800-749-7273

If you are a client of Vanguard’s Institutional Division:

The Vanguard Group

Institutional Investor Information Department P.O. Box 2900 Valley Forge, PA 19482-2900 Telephone: 888-809-8102; Text telephone for people with hearing impairment: 800-749-7273

If you are a current Vanguard shareholder and would like information about your account, account transactions, and/or account statements, please call:

Client Services Department

Telephone: 800-662-2739; Text telephone for people with hearing impairment: 800-749-7273

Information Provided by the Securities and Exchange Commission (SEC)

You can review and copy information about the Fund (including the SAI) at the SEC’s Public Reference Room in Washington, DC. To find out more about this public service, call the SEC at 202-551-8090. Reports and other information about the Fund are also available in the EDGAR database on the SEC’s website at www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following email address: [email protected], or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

Fund’s Investment Company Act file number: 811-06093

© 2018 The Vanguard Group, Inc. All rights reserved. Vanguard Marketing Corporation, Distributor.

I 854 042018

Fund Summary

Investment Objective

The Fund seeks to track the performance of a benchmark index that measures the investment return of the overall stock market.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Institutional Shares or Institutional Plus Shares of the Fund.

Annual Fund Operating Expenses

(Expenses that you pay each year as a percentage of the value of your investment)

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Examples

The following examples are intended to help you compare the cost of investing in the Fund’s Institutional Shares or Institutional Plus Shares with the cost of investing in other mutual funds. They illustrate the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Fund’s shares. These examples assume that the shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense examples, reduce the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was X% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the CRSP US Total Market Index, which represents approximately 100% of the investable U.S. stock market and includes large-, mid-, small-, and micro-cap stocks regularly traded on the New York Stock Exchange and Nasdaq. The Fund invests by sampling the Index, meaning that it holds a broadly diversified collection of securities that, in the aggregate, approximates the full Index in terms of key characteristics. These key characteristics include industry weightings and market capitalization, as well as certain financial measures such as price/earnings ratio and dividend yield.

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Principal Risks

An investment in the Fund could lose money over short or long periods of time. You should expect the Fund’s share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund’s performance:

• Stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. In addition, the Fund’s target index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

• Index sampling risk, which is the chance that the securities selected for the Fund, in the aggregate, will not provide investment performance matching that of the Fund‘s target index. Index sampling risk for the Fund should be low.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Annual Total Returns

The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund‘s Institutional Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the share classes presented compare with those of the Fund‘s target index and other comparative indexes, which have investment characteristics similar to those of the Fund. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.

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During the periods shown in the bar chart, the highest return for a calendar quarter was XX.XX% (quarter ended xxxx), and the lowest return for a quarter was XX.XX% (quarter ended xxxx).

Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are shown only for the Institutional Shares and may differ for each share class. After-tax returns are not relevant for a shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.

Investment Advisor

The Vanguard Group, Inc. (Vanguard)

Portfolio Managers

Walter Nejman, Portfolio Manager at Vanguard. He has co-managed the Fund since 2016.

Gerard C. O’Reilly, Principal of Vanguard. He has co-managed the Fund since 2016.

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Purchase and Sale of Fund Shares

You may purchase or redeem shares online through our website (vanguard.com), by mail (The Vanguard Group, P.O. Box 1110, Valley Forge, PA 19482-1110), or by telephone (800-662-2739). The minimum investment amount required to open and maintain a Fund account for Institutional Shares or Institutional Plus Shares is $5 million or $100 million, respectively. The minimum investment amount required to add to an existing Fund account is generally $1. If you are investing through an employer-sponsored retirement or savings plan, your plan administrator or your benefits office can provide you with detailed information on how you can invest through your plan.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gain. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply.

Payments to Financial Intermediaries

The Fund and its investment advisor do not pay financial intermediaries for sales of Fund shares.

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Investing in Index Funds

What Is Indexing?

Indexing is an investment strategy for tracking the performance of a specified market benchmark, or “index.” An index is a group of securities whose overall performance is used as a standard to measure the investment performance of a particular market. There are many types of indexes. Some represent entire markets—such as the U.S. stock market or the U.S. bond market. Other indexes cover market segments—such as small-capitalization stocks or short-term bonds. The index sponsor determines the securities to include in the index, the weighting of each security in the index, and the appropriate time to make changes to the composition of the index. One cannot invest directly in an index.

An index fund seeks to hold all, or a representative sample, of the securities that make up its target index. Index funds attempt to mirror the performance of the target index, for better or worse. However, an index fund generally does not perform exactly like its target index. For example, index funds have operating expenses and transaction costs. Market indexes do not, and therefore they will usually have a slight performance advantage over funds that track them.

Index funds typically have the following characteristics:

• Variety of investments. Index funds generally invest in the securities of a variety of companies and industries.

• Relative performance consistency. Because they seek to track market benchmarks, index funds usually do not perform dramatically better or worse than their benchmarks.

• Low cost. Index funds are generally inexpensive to run compared with actively managed funds. They have low or no research costs and typically keep trading activity—and thus brokerage commissions and other transaction costs—to a minimum compared with actively managed funds.

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More on the Fund

This prospectus describes the principal risks you would face as a Fund shareholder. It is important to keep in mind one of the main axioms of investing: generally, the higher the risk of losing money, the higher the potential reward. The reverse, also, is generally true: the lower the risk, the lower the potential reward. As you consider an investment in any mutual fund, you should take into account your personal tolerance for fluctuations in the securities markets. Look for this symbol throughout the prospectus. It is used to mark detailed information about the more significant risks that you would confront as a Fund shareholder. To highlight terms and concepts important to mutual fund investors, we have provided Plain Talk^® explanations along the way. Reading the prospectus will help you decide whether the Fund is the right investment for you. We suggest that you keep this prospectus for future reference.

Share Class Overview

This prospectus offers the Fund’s Institutional Shares and Institutional Plus Shares, which are generally for investors who invest a minimum of $5 million and $100 million, respectively.

Both share classes offered by the Fund have the same investment objective, strategies, and policies. However, different share classes have different expenses; as a result, their investment performances will differ.

A Similar but Distinct Vanguard Fund

The Fund offered by this prospectus should not be confused with Vanguard Total Stock Market Index Fund, a separate Vanguard fund that also seeks to track the performance of the CRSP US Total Market Index. Both funds invest in representative samples of the stocks that make up their target indexes, but specific stocks held by the funds will differ. This index sampling strategy, combined with differences in the funds’ respective cash flows and expenses, is expected to produce slightly different investment performance by the funds. Although Vanguard Institutional Total Stock Market Index Fund offers lower expenses, investors should not necessarily expect this Fund to outperform Vanguard Total Stock Market Index Fund over any particular period of time. To obtain a prospectus for Vanguard Total Stock Market Index Fund, please call 800-662-7447.

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The following sections explain the principal investment strategies and policies that the Fund uses in pursuit of its objective. The Fund‘s board of trustees, which oversees the Fund’s management, may change investment strategies or policies in the interest of shareholders without a shareholder vote, unless those strategies or policies are designated as fundamental. Under normal circumstances, the Fund will invest at least 80% of its assets in the stocks that make up its target index. The Fund may change its 80% policy only upon 60 days‘ notice to shareholders.

Market Exposure

The Fund is subject to stock market risk, which is the chance that stock prices overall will decline. Stock markets tend to move in cycles, with periods of rising prices and periods of falling prices. In addition, the Fund’s target index may, at times, become focused in stocks of a particular market sector, which would subject the Fund to proportionately higher exposure to the risks of that sector.

To illustrate the volatility of stock prices, the following table shows the best, worst, and average annual total returns for the U.S. stock market over various periods as

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measured by the S&P 500 Index, a widely used barometer of U.S. stock market activity. Total returns consist of dividend income plus change in market price. Note that the returns shown do not include the costs of buying and selling stocks or other expenses that a real-world investment portfolio would incur.

U.S. Stock Market Average Annual Returns
(1926–2017)

The table covers all of the rolling 1-, 5-, 10-, and 20-year periods from 1926 through 2017. You can see, for example, that although the average annual return on common stocks for all of the 5-year periods was XX.X%, average annual returns for individual 5-year periods ranged from XX.X% (from 1928 through 1932) to XX.X% (from 1995 through 1999). These average annual returns reflect past performance of common stocks; you should not regard them as an indication of future performance of either the stock market as a whole or the Fund in particular.

Keep in mind that the S&P 500 Index tracks mainly large-cap stocks. Historically, mid- and small-cap stocks (such as those held by the Fund) have been more volatile than—and at times have performed quite differently from—the large-cap stocks of the S&P 500 Index.

Stocks of publicly traded companies and funds that invest in stocks are often classified according to market value, or market capitalization. These classifications typically include small-cap, mid-cap, and large-cap. It is important to understand that market capitalization ranges change over time. Also, interpretations of size vary, and there are no “official” definitions of small-, mid-, and large-cap, even among Vanguard fund advisors. The asset-weighted median market capitalization of the Fund’s stock holdings as of December 31, 2017, was $X.X billion.

Security Selection

The Fund attempts to track the investment performance of a benchmark index that measures the return of the overall stock market. The Fund uses a sampling method of indexing, meaning that the Fund’s advisor, using computer programs, generally selects from the target index a representative sample of securities that will resemble the target index in terms of key characteristics. These include industry weightings, market capitalization, and other financial characteristics of stocks.

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The Fund is subject to index sampling risk, which is the chance that the securities selected for the Fund, in the aggregate, will not provide investment performance matching that of the Fund’s target index. Index sampling risk for the Fund should be low.

Other Investment Policies and Risks

The Fund reserves the right to substitute a different index for the index it currently tracks if the current index is discontinued, if the Fund‘s agreement with the sponsor of its target index is terminated, or for any other reason determined in good faith by the Fund’s board of trustees. In any such instance, the substitute index would represent the same market segment as the current index.

The Fund may invest in foreign securities to the extent necessary to carry out its investment strategy of holding a representative sample of the stocks that make up the index it tracks. It is not expected that the Fund will invest more than 5% of its assets in foreign securities.

To track its target index as closely as possible, the Fund attempts to remain fully invested in stocks. To help stay fully invested and to reduce transaction costs, the Fund may invest, to a limited extent, in derivatives, including equity futures. The Fund may also use derivatives such as total return swaps to obtain exposure to a stock, a basket of stocks, or an index. Generally speaking, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, a bond, or a currency), a physical asset (such as gold, oil, or wheat), a market index (such as the S&P 500 Index), or a reference rate (such as LIBOR). Investments in derivatives may subject the Fund to risks different from, and possibly greater than, those of investments directly in the underlying securities or assets. The Fund will not use derivatives for speculation or for the purpose of leveraging (magnifying) investment returns.

Cash Management

The Fund‘s daily cash balance may be invested in one or more Vanguard CMT Funds, which are low-cost money market funds. When investing in a Vanguard CMT Fund, the Fund bears its proportionate share of the expenses of the CMT Fund in which it invests. Vanguard receives no additional revenue from Fund assets invested in a Vanguard CMT Fund.

Methods Used to Meet Redemption Requests

Under normal circumstances, the Fund typically expects to meet redemptions with other positive cash flows. When this is not an option, the Fund seeks to maintain its risk exposure by selling a cross section of the Fund’s holdings to meet redemptions, while also factoring in transaction costs. Additionally, the Fund may work with larger clients to implement their redemptions in a manner that is least disruptive to the portfolio; see

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“Potentially disruptive redemptions” under Redeeming Shares in the Investing With Vanguard section.

Under certain circumstances, including under stressed market conditions, there are additional tools that the Fund may use in order to meet redemptions, including advancing the settlement of market trades with counterparties to match investor redemption payments or delaying settlement of an investor’s transaction to match trade settlement within regulatory requirements. The Fund may also suspend payment of redemption proceeds for up to seven days; see “Emergency circumstances” under Redeeming Shares in the Investing With Vanguard section. Additionally under these unusual circumstances, the Fund may borrow money (subject to certain regulatory conditions and if available under board-approved procedures) through an interfund lending facility or through a bank line-of-credit, including a joint committed credit facility, in order to meet redemption requests.

Temporary Investment Measures

The Fund may temporarily depart from its normal investment policies and strategies when the advisor believes that doing so is in the Fund‘s best interest, so long as the strategy or policy employed is consistent with the Fund‘s investment objective. For instance, the Fund may invest beyond its normal limits in derivatives or exchange-traded funds that are consistent with the Fund‘s objective when those instruments are more favorably priced or provide needed liquidity, as might be the case when the Fund receives large cash flows that it cannot prudently invest immediately.

Frequent Trading or Market-Timing

Background. Some investors try to profit from strategies involving frequent trading of mutual fund shares, such as market-timing. For funds holding foreign securities, investors may try to take advantage of an anticipated difference between the price of the fund’s shares and price movements in overseas markets, a practice also known as time-zone arbitrage. Investors also may try to engage in frequent trading of funds holding investments such as small-cap stocks and high-yield bonds. As money is shifted into and out of a fund by a shareholder engaging in frequent trading, the fund incurs costs for buying and selling securities, resulting in increased brokerage and administrative costs. These costs are borne by all fund shareholders, including the long-term investors who do not generate the costs. In addition, frequent trading may interfere with an advisor’s ability to efficiently manage the fund.

Policies to address frequent trading. The Vanguard funds (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) do not knowingly accommodate frequent trading. The board of trustees of each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities

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Index Fund) has adopted policies and procedures reasonably designed to detect and discourage frequent trading and, in some cases, to compensate the fund for the costs associated with it. These policies and procedures do not apply to ETF Shares because frequent trading in ETF Shares generally does not disrupt portfolio management or otherwise harm fund shareholders. Although there is no assurance that Vanguard will be able to detect or prevent frequent trading or market-timing in all circumstances, the following policies have been adopted to address these issues:

• Each Vanguard fund reserves the right to reject any purchase request—including exchanges from other Vanguard funds—without notice and regardless of size. For example, a purchase request could be rejected because the investor has a history of frequent trading or if Vanguard determines that such purchase may negatively affect a fund’s operation or performance.

• Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) generally prohibits, except as otherwise noted in the Investing With Vanguard section, an investor’s purchases or exchanges into a fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account.

• Certain Vanguard funds charge shareholders purchase and/or redemption fees on transactions.

See the Investing With Vanguard section of this prospectus for further details on Vanguard’s transaction policies.

Each Vanguard fund (other than retail and government money market funds), in determining its net asset value, will use fair-value pricing when appropriate, as described in the Share Price section. Fair-value pricing may reduce or eliminate the profitability of certain frequent-trading strategies.

Do not invest with Vanguard if you are a market-timer.

Turnover Rate

Although the Fund generally seeks to invest for the long term, it may sell securities regardless of how long they have been held. Generally, an index fund sells securities in response to redemption requests or to changes in the composition of its target index. Turnover rates for large-cap stock index funds tend to be low because large-cap indexes typically do not change significantly from year to year. Turnover rates for mid-cap and small-cap stock index funds tend to be higher (although still relatively low, compared with actively managed stock funds) because the indexes they track are more likely to change as a result of companies merging, growing, or failing. The Financial Highlights section of this prospectus shows historical turnover rates for the Fund. A turnover rate of 100%, for example, would mean that the Fund had sold and replaced securities valued at 100% of its net assets within a one-year period.

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The Fund and Vanguard

The Fund is a member of The Vanguard Group, a family of over 200 funds holding assets of approximately $X.X trillion. All of the funds that are members of The Vanguard Group (other than funds of funds) share in the expenses associated with administrative services and business operations, such as personnel, office space, and equipment.

Vanguard Marketing Corporation provides marketing services to the funds. Although shareholders do not pay sales commissions or 12b-1 distribution fees, each fund (other than a fund of funds) or each share class of a fund (in the case of a fund with multiple share classes) pays its allocated share of the Vanguard funds’ marketing costs.

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Plain Talk About Vanguard’s Unique Corporate Structure

The Vanguard Group is truly a mutual mutual fund company. It is owned jointly by the funds it oversees and thus indirectly by the shareholders in those funds. Most other mutual funds are operated by management companies that may be owned by one person, by a private group of individuals, or by public investors who own the management company’s stock. The management fees charged by these companies include a profit component over and above the companies’ cost of providing services. By contrast, Vanguard provides services to its member funds on an at-cost basis, with no profit component, which helps to keep the funds’ expenses low.

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Investment Advisor

The Vanguard Group, Inc. (Vanguard), P.O. Box 2600, Valley Forge, PA 19482, which began operations in 1975, serves as advisor to the Fund through its Equity Index Group. As of December 31, 2017, Vanguard served as advisor for approximately $X.X trillion in assets. Vanguard provides investment advisory services to the Fund on an at-cost basis, subject to the supervision and oversight of the trustees and officers of the Fund.

Under the terms of an SEC exemption, the Fund‘s board of trustees may, without prior approval from shareholders, change the terms of an advisory agreement with a third-party investment advisor or hire a new third-party investment advisor—either as a replacement for an existing advisor or as an additional advisor. Any significant change in the Fund’s advisory arrangements will be communicated to shareholders in writing. As the Fund‘s sponsor and overall manager, Vanguard may provide investment advisory services to the Fund, on an at-cost basis, at any time. Vanguard may also recommend to the board of trustees that an advisor be hired, terminated, or replaced or that the terms of an existing advisory agreement be revised. The Fund has filed an application seeking a similar SEC exemption with respect to investment advisors that are wholly owned subsidiaries of Vanguard. If granted, the Fund may rely on the new SEC relief.

The managers primarily responsible for the day-to-day management of the Fund are:

Walter Nejman, Portfolio Manager at Vanguard. He has been with Vanguard since 2005, has worked in investment management since 2008, and has co-managed the Fund since 2016. Education: B.A., Arcadia University; M.B.A., Villanova University.

Gerard C. O’Reilly, Principal of Vanguard. He has been with Vanguard since 1992, has managed investment portfolios since 1994, and has co-managed the Fund since 2016. Education: B.S., Villanova University.

The Statement of Additional Information provides information about each portfolio manager’s compensation, other accounts under management, and ownership of shares of the Fund.

Dividends, Capital Gains, and Taxes

Fund Distributions

The Fund distributes to shareholders virtually all of its net income (interest and dividends, less expenses) as well as any net short-term or long-term capital gains realized from the sale of its holdings. Income dividends generally are distributed quarterly in March, June, September, and December; capital gains distributions, if any,

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generally occur annually in December. In addition, the Fund may occasionally make a supplemental distribution at some other time during the year.

You can receive distributions of income or capital gains in cash, or you can have them automatically reinvested in more shares of the Fund. However, if you are investing through an employer-sponsored retirement or savings plan, your distributions will be automatically reinvested in additional Fund shares.

Basic Tax Points

Investors in taxable accounts should be aware of the following basic federal income tax points:

• Distributions are taxable to you whether or not you reinvest these amounts in additional Fund shares.

• Distributions declared in December—if paid to you by the end of January—are taxable as if received in December.

• Any dividend distribution or short-term capital gains distribution that you receive is taxable to you as ordinary income. If you are an individual and meet certain holding-period requirements with respect to your Fund shares, you may be eligible for reduced tax rates on “qualified dividend income,” if any, distributed by the Fund.

• Any distribution of net long-term capital gains is taxable to you as long-term capital gains, no matter how long you have owned shares in the Fund.

• Capital gains distributions may vary considerably from year to year as a result of the Fund‘s normal investment activities and cash flows.

• A sale or exchange of Fund shares is a taxable event. This means that you may have a capital gain to report as income, or a capital loss to report as a deduction, when you

complete your tax return.

• Any conversion between classes of shares of the same fund is a nontaxable event. By contrast, an exchange between classes of shares of different funds is a taxable event.

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• Vanguard (or your intermediary) will send you a statement each year showing the tax status of all of your distributions.

Individuals, trusts, and estates whose income exceeds certain threshold amounts are subject to a 3.8% Medicare contribution tax on “net investment income.” Net investment income takes into account distributions paid by the Fund and capital gains from any sale or exchange of Fund shares.

Dividend distributions and capital gains distributions that you receive, as well as your gains or losses from any sale or exchange of Fund shares, may be subject to state and local income taxes.

This prospectus provides general tax information only. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply. Please consult your tax advisor for detailed information about any tax consequences for you.

General Information

Backup withholding. By law, Vanguard must withhold 24% of any taxable distributions or redemptions from your account if you do not:

• Provide your correct taxpayer identification number.

• Certify that the taxpayer identification number is correct.

• Confirm that you are not subject to backup withholding.

Similarly, Vanguard (or your intermediary) must withhold taxes from your account if the IRS instructs us to do so.

Foreign investors. Vanguard funds offered for sale in the United States (Vanguard U.S. funds), including the Fund offered in this prospectus, are not widely available outside the

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United States. Non-U.S. investors should be aware that U.S. withholding and estate taxes and certain U.S. tax reporting requirements may apply to any investments in Vanguard U.S. funds. Foreign investors should visit the Non-U.S. Investors page on our website at vanguard.com for information on Vanguard’s non-U.S. products.

Invalid addresses. If a dividend distribution or capital gains distribution check mailed to your address of record is returned as undeliverable, Vanguard will automatically reinvest the distribution and all future distributions until you provide us with a valid mailing address. Reinvestments will receive the net asset value calculated on the date of the reinvestment.

Share Price

Share price, also known as net asset value (NAV), is calculated each business day as of the close of regular trading on the New York Stock Exchange (NYSE), generally 4 p.m., Eastern time. In the rare event the NYSE experiences unanticipated trade disruptions and is unavailable at the close of the trading day, NAVs will be calculated as of the close of regular trading on the Nasdaq (or another alternate exchange if the Nasdaq is unavailable, as determined at Vanguard's discretion), generally 4 p.m., Eastern time. Each share class has its own NAV, which is computed by dividing the total assets, minus liabilities, allocated to the share class by the number of Fund shares outstanding for that class. On U.S. holidays or other days when the NYSE is closed, the NAV is not calculated, and the Fund does not sell or redeem shares. However, on those days the value of the Fund’s assets may be affected to the extent that the Fund holds securities that change in value on those days (such as foreign securities that trade on foreign markets that are open).

Stocks held by a Vanguard fund are valued at their market value when reliable market quotations are readily available from the principal exchange or market on which they are traded. Such securities are generally valued at their official closing price, the last reported sales price, or if there were no sales that day, the mean between the closing bid and asking prices. When a fund determines that market quotations either are not readily available or do not accurately reflect the value of a security, the security is priced at its fair value (the amount that the owner might reasonably expect to receive upon the current sale of the security).

The values of any foreign securities held by a fund are converted into U.S. dollars using an exchange rate obtained from an independent third party as of the close of regular trading on the NYSE. The values of any mutual fund shares, including institutional money market fund shares, held by a fund are based on the NAVs of the shares. The values of any ETF shares or closed-end fund shares held by a fund are based on the market value of the shares.

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A fund also will use fair-value pricing if the value of a security it holds has been materially affected by events occurring before the fund’s pricing time but after the close of the principal exchange or market on which the security is traded. This most commonly occurs with foreign securities, which may trade on foreign exchanges that close many hours before the fund’s pricing time. Intervening events might be company-specific (e.g., earnings report, merger announcement) or country-specific or regional/global (e.g., natural disaster, economic or political news, act of terrorism, interest rate change). Intervening events include price movements in U.S. markets that exceed a specified threshold or that are otherwise deemed to affect the value of foreign securities.

Fair-value pricing may be used for domestic securities—for example, if (1) trading in a security is halted and does not resume before the fund’s pricing time or a security does not trade in the course of a day and (2) the fund holds enough of the security that its price could affect the NAV.

Fair-value prices are determined by Vanguard according to procedures adopted by the board of trustees. When fair-value pricing is employed, the prices of securities used by a fund to calculate the NAV may differ from quoted or published prices for the same securities.

Vanguard fund share prices are published daily on our website at vanguard.com/prices.

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Financial Highlights

The following financial highlights tables are intended to help you understand the Fund’s financial performance for the periods shown, and certain information reflects financial results for a single Fund share. The total returns in each table represent the rate that an investor would have earned or lost each period on an investment in the Fund (assuming reinvestment of all distributions). This information has been obtained from the financial statements audited by *, an independent registered public accounting firm, whose report—along with the Fund’s financial statements—is included in the Fund‘s most recent annual report to shareholders. You may obtain a free copy of the latest annual or semiannual report by visiting vanguard.com or by contacting Vanguard by telephone or mail.

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1 Net investment income per share and the ratio of net investment income to average net assets include $0.140 and 0.31%, respectively, resulting from income received from Medtronic plc in January 2015.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares.

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Institutional Total Stock Market Index Fund Institutional Plus Shares

1 Net investment income per share and the ratio of net investment income to average net assets include $0.140 and 0.31%, respectively, resulting from income received from Medtronic plc in January 2015.

2 Excludes the value of portfolio securities received or delivered as a result of in-kind purchases or redemptions of the Fund’s capital shares.

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Investing With Vanguard

This section of the prospectus explains the basics of doing business with Vanguard. Vanguard fund shares can be held directly with Vanguard or indirectly through an intermediary, such as a bank, a broker, or an investment advisor. If you hold Vanguard fund shares directly with Vanguard, you should carefully read each topic within this section that pertains to your relationship with Vanguard. If you hold Vanguard fund shares indirectly through an intermediary (including shares held through a Vanguard brokerage account), please see Investing With Vanguard Through Other Firms, and also refer to your account agreement with the intermediary for information about transacting in that account. If you hold Vanguard fund shares through an employer-sponsored retirement or savings plan, please see Employer-Sponsored Plans. Vanguard reserves the right to change the following policies without notice. Please call or check online for current information. See Contacting Vanguard.

For Vanguard fund shares held directly with Vanguard, each fund you hold in an account is a separate “fund account.” For example, if you hold three funds in a nonretirement account titled in your own name, two funds in a nonretirement account titled jointly with your spouse, and one fund in an individual retirement account, you have six fund accounts—and this is true even if you hold the same fund in multiple accounts. Note that each reference to “you” in this prospectus applies to any one or more registered account owners or persons authorized to transact on your account.

Purchasing Shares

Vanguard reserves the right, without notice, to increase or decrease the minimum amount required to open, convert shares to, or maintain a fund account or to add to an existing fund account.

Investment minimums may differ for certain categories of investors.

Account Minimums for Institutional Shares and Institutional Plus Shares To open and maintain an account. Institutional Shares—$5 million; Institutional Plus Shares—$100 million. If you request Institutional Plus Shares when you open a new account but the investment amount does not meet the account minimum for Institutional Plus shares, your investment will be placed in Institutional Shares of the Fund. Institutional clients should contact Vanguard for information on special eligibility rules that may apply to them.

Certain Vanguard institutional clients may meet the minimum investment amount by aggregating separate accounts within the same Fund. This aggregation policy does not apply to financial intermediaries.

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Vanguard may charge additional recordkeeping fees for institutional clients whose accounts are recordkept by Vanguard. Please contact your Vanguard representative to determine whether additional recordkeeping fees apply to your account.

To add to an existing account. Generally $1.

How to Initiate a Purchase Request

Be sure to check Exchanging Shares, Frequent-Trading Limitations, and Other Rules You Should Know before placing your purchase request.

Online. You may open certain types of accounts, request a purchase of shares, and request an exchange through our website or our mobile application if you are registered for online access.

By telephone. You may call Vanguard to begin the account registration process or request that the account-opening forms be sent to you. You may also call Vanguard to request a purchase of shares in your account or to request an exchange. See

Contacting Vanguard.

By mail. You may send Vanguard your account registration form and check to open a new fund account. To add to an existing fund account, you may send your check with an Invest-by-Mail form (from a transaction confirmation or your account statement), with a deposit slip (available online), or with a written request. You may also send a written request to Vanguard to make an exchange. For a list of Vanguard addresses, see Contacting Vanguard.

How to Pay for a Purchase

By electronic bank transfer. You may purchase shares of a Vanguard fund through an electronic transfer of money from a bank account. To establish the electronic bank transfer service on an account, you must designate the bank account online, complete a special form, or fill out the appropriate section of your account registration form. After the service is set up on your account, you can purchase shares by electronic bank transfer on a regular schedule (Automatic Investment Plan) or upon request. Your purchase request can be initiated online (if you are registered for online access), by telephone, or by mail.

By wire. Wiring instructions vary for different types of purchases. Please call Vanguard for instructions and policies on purchasing shares by wire. See Contacting Vanguard.

By check. You may make initial or additional purchases to your fund account by sending a check or by utilizing our mobile application if you are registered for online access. Also see How to Initiate a Purchase Request. Make your check payable to Vanguard and include the appropriate fund number (e.g., Vanguard—xx). For a list of Fund numbers (for share classes in this prospectus), see Additional Information.

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By exchange. You may purchase shares of a Vanguard fund using the proceeds from the simultaneous redemption of shares of another Vanguard fund. You may initiate an exchange online (if you are registered for online access), by telephone, or by mail. See

Exchanging Shares.

Trade Date

The trade date for any purchase request received in good order will depend on the day and time Vanguard receives your request, the manner in which you are paying, and the type of fund you are purchasing. Your purchase will be executed using the net asset value (NAV) as calculated on the trade date. NAVs are calculated only on days that the New York Stock Exchange (NYSE) is open for trading (a business day).

For purchases by check into all funds other than money market funds and for purchases by exchange, wire, or electronic bank transfer (not using an Automatic Investment Plan) into all funds: If the purchase request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date for the purchase will be the same day. If the purchase request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date for the purchase will be the next business day.

For purchases by check into money market funds: If the purchase request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date for the purchase will be the next business day. If the purchase request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date for the purchase will be the second business day following the day Vanguard receives the purchase request. Because money market instruments must be purchased with federal funds and it takes a money market mutual fund one business day to convert check proceeds into federal funds, the trade date for the purchase will be one business day later than for other funds.

For purchases by electronic bank transfer using an Automatic Investment Plan: Your trade date generally will be the date you selected for withdrawal of funds from your designated bank account. Your bank account generally will be debited on the business day after your trade date. If the date you selected for withdrawal of funds from your bank account falls on a weekend, holiday, or other nonbusiness day, your trade date generally will be the previous business day. For retirement accounts, if the date you selected for withdrawal of funds from your designated bank account falls on the last business day of the year, your trade date will be the first business day of the following year. Please note that if you select the first of the month for automated withdrawals from your designated bank account, trades designated for January 1 will receive the next business day’s trade date.

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If your purchase request is not accurate and complete, it may be rejected. See Other Rules You Should Know—Good Order.

For further information about purchase transactions, consult our website at vanguard.com or see Contacting Vanguard.

Other Purchase Rules You Should Know

Check purchases. All purchase checks must be written in U.S. dollars and must be drawn on a U.S. bank. Vanguard does not accept cash, traveler’s checks, starter checks, or money orders. In addition, Vanguard may refuse checks that are not made payable to Vanguard.

New accounts. We are required by law to obtain from you certain personal information that we will use to verify your identity. If you do not provide the information, we may not be able to open your account. If we are unable to verify your identity, Vanguard reserves the right, without notice, to close your account or take such other steps as we deem reasonable. Certain types of accounts may require additional documentation.

Refused or rejected purchase requests. Vanguard reserves the right to stop selling fund shares or to reject any purchase request at any time and without notice, including, but not limited to, purchases requested by exchange from another Vanguard fund. This also includes the right to reject any purchase request because the investor has a history of frequent trading or because the purchase may negatively affect a fund’s operation or performance.

Large purchases. Call Vanguard before attempting to invest a large dollar amount.

No cancellations. Vanguard will not accept your request to cancel any purchase request once processing has begun. Please be careful when placing a purchase request.

Converting Shares

When a conversion occurs, you receive shares of one class in place of shares of another class of the same fund. At the time of conversion, the dollar value of the “new” shares you receive equals the dollar value of the “old” shares that were converted. In other words, the conversion has no effect on the value of your investment in the fund at the time of the conversion. However, the number of shares you own after the conversion may be greater than or less than the number of shares you owned before the conversion, depending on the NAVs of the two share classes.

Vanguard will not accept your request to cancel any self-directed conversion request once processing has begun. Please be careful when placing a conversion request.

A conversion between share classes of the same fund is a nontaxable event.

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Trade Date

The trade date for any conversion request received in good order will depend on the day and time Vanguard receives your request. Your conversion will be executed using the NAVs of the different share classes on the trade date. NAVs are calculated only on days that the NYSE is open for trading (a business day).

For a conversion request received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. For a conversion request received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day. See Other Rules You Should Know.

Conversions From Institutional Shares to Institutional Plus Shares

You may convert Institutional Shares to Institutional Plus Shares of the Fund, provided that your account balance is at least $100 million.

Mandatory Conversions to Institutional Shares

If an account no longer meets the balance requirements for Institutional Plus Shares, Vanguard may automatically convert the shares in the account to Institutional Shares. A decline in the account balance because of market movement may result in such a conversion. Vanguard will notify the investor in writing before any mandatory conversion occurs.

Redeeming Shares

How to Initiate a Redemption Request

Be sure to check Exchanging Shares, Frequent-Trading Limitations, and Other Rules You Should Know before placing your redemption request.

Online. You may request a redemption of shares or request an exchange through our website or our mobile application if you are registered for online access.

By telephone. You may call Vanguard to request a redemption of shares or an exchange. See Contacting Vanguard.

By mail. You may send a written request to Vanguard to redeem from a fund account or to make an exchange. See Contacting Vanguard.

How to Receive Redemption Proceeds

By electronic bank transfer. You may have the proceeds of a fund redemption sent directly to a designated bank account. To establish the electronic bank transfer service on an account, you must designate a bank account online, complete a special form, or fill out the appropriate section of your account registration form. After the service is set

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up on your account, you can redeem shares by electronic bank transfer on a regular schedule (Automatic Withdrawal Plan) or upon request. Your redemption request can be initiated online (if you are registered for online access), by telephone, or by mail.

By wire. To receive your proceeds by wire, you may instruct Vanguard to wire your redemption proceeds ($100 minimum) to a previously designated bank account. To establish the wire redemption service, you generally must designate a bank account online, complete a special form, or fill out the appropriate section of your account registration form.

Please note that Vanguard charges a $10 wire fee for outgoing wire redemptions. The fee is assessed in addition to, rather than being withheld from, redemption proceeds and is paid directly to the fund. For example, if you redeem $100 via a wire, you will receive the full $100, and your fund account will also be assessed the $10 fee by redeeming additional fund shares. If you redeem your entire fund account, your redemption proceeds will be reduced by the fee amount. The wire fee does not apply to accounts held by Flagship and Flagship Select clients; accounts held through intermediaries, including Vanguard Brokerage Services; or accounts held by institutional clients.

By exchange. You may have the proceeds of a Vanguard fund redemption invested directly in shares of another Vanguard fund. You may initiate an exchange online (if you are registered for online access), by telephone, or by mail. See Exchanging Shares.

By check. If you have not chosen another redemption method, Vanguard will mail you a redemption check, generally payable to all registered account owners, normally within two business days of your trade date, and generally to the address of record.

Trade Date

The trade date for any redemption request received in good order will depend on the day and time Vanguard receives your request and the manner in which you are redeeming. Your redemption will be executed using the NAV as calculated on the trade date. NAVs are calculated only on days that the NYSE is open for trading (a business day).

For redemptions by check, exchange, or wire: If the redemption request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. If the redemption request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day.

• Note on timing of wire redemptions from money market funds: For telephone requests received by Vanguard on a business day before 10:45 a.m., Eastern time (2 p.m., Eastern time, for Vanguard Prime Money Market Fund; 12:30 p.m., Eastern time, for Vanguard Federal Money Market Fund), the redemption proceeds

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generally will leave Vanguard by the close of business the same day. For telephone requests received by Vanguard on a business day after those cut-off times, or on a nonbusiness day, and for all requests other than by telephone, the redemption proceeds generally will leave Vanguard by the close of business on the next business day.

• Note on timing of wire redemptions from all other funds: For requests received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the redemption proceeds generally will leave Vanguard by the close of business on the next business day. For requests received by Vanguard on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the redemption proceeds generally will leave Vanguard by the close of business on the second business day after Vanguard receives the request.

For redemptions by electronic bank transfer using an Automatic Withdrawal Plan: Your trade date generally will be the date you selected for withdrawal of funds (redemption of shares) from your Vanguard account. Proceeds of redeemed shares generally will be credited to your designated bank account two business days after your trade date. If the date you selected for withdrawal of funds from your Vanguard account falls on a weekend, holiday, or other nonbusiness day, your trade date generally will be the previous business day. For retirement accounts, if the date you selected for withdrawal of funds from your Vanguard account falls on the last day of the year and if that date is a holiday, your trade date will be the first business day of the following year. Please note that if you designate the first of the month for automated withdrawals, trades designated for January 1 will receive the next business day’s trade date.

For redemptions by electronic bank transfer not using an Automatic Withdrawal Plan: If the redemption request is received by Vanguard on a business day before the close of regular trading on the NYSE (generally 4 p.m., Eastern time), the trade date will be the same day. If the redemption request is received on a business day after the close of regular trading on the NYSE, or on a nonbusiness day, the trade date will be the next business day.

If your redemption request is not accurate and complete, it may be rejected. If we are unable to send your redemption proceeds by wire or electronic bank transfer because the receiving institution rejects the transfer, Vanguard will make additional efforts to complete your transaction. If Vanguard is still unable to complete the transaction, we may send the proceeds of the redemption to you by check, generally payable to all registered account owners, or use your proceeds to purchase new shares of the fund from which you sold shares for the purpose of the wire or electronic bank transfer transaction. See Other Rules You Should Know—Good Order.

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If your redemption request is received in good order, we typically expect that redemption proceeds will be paid by the Fund within one business day of the trade date; however, in certain circumstances, investors may experience a longer settlement period at the time of the transaction. For further information, see “Potentially disruptive redemptions” and “Emergency circumstances.”

For further information about redemption transactions, consult our website at vanguard.com or see Contacting Vanguard.

Other Redemption Rules You Should Know

Documentation for certain accounts. Special documentation may be required to redeem from certain types of accounts, such as trust, corporate, nonprofit, or retirement accounts. Please call us before attempting to redeem from these types of accounts.

Potentially disruptive redemptions. Vanguard reserves the right to pay all or part of a redemption in kind—that is, in the form of securities—if we reasonably believe that a cash redemption would negatively affect the fund’s operation or performance or that the shareholder may be engaged in market-timing or frequent trading. Under these circumstances, Vanguard also reserves the right to delay payment of the redemption proceeds for up to seven calendar days. By calling us before you attempt to redeem a large dollar amount, you may avoid in-kind or delayed payment of your redemption. Please see Frequent-Trading Limitations for information about Vanguard’s policies to limit frequent trading.

Recently purchased shares. Although you can redeem shares at any time, proceeds may not be made available to you until the fund collects payment for your purchase. This may take up to seven calendar days for shares purchased by check or by electronic bank transfer. If you have written a check on a fund with checkwriting privileges, that check may be rejected if your fund account does not have a sufficient available balance.

Address change. If you change your address online or by telephone, there may be up to a 15-day restriction on your ability to request check redemptions online and by telephone. You can request a redemption in writing at any time. Confirmations of address changes are sent to both the old and new addresses.

Payment to a different person or address. At your request, we can make your redemption check payable, or wire your redemption proceeds, to a different person or send it to a different address. However, this generally requires the written consent of all registered account owners and may require additional documentation, such as a signature guarantee or a notarized signature. You may obtain a signature guarantee from some commercial or savings banks, credit unions, trust companies, or member firms of a U.S. stock exchange.

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No cancellations. Vanguard will not accept your request to cancel any redemption request once processing has begun. Please be careful when placing a redemption request.

Emergency circumstances. Vanguard funds can postpone payment of redemption proceeds for up to seven calendar days. In addition, Vanguard funds can suspend redemptions and/or postpone payments of redemption proceeds beyond seven calendar days at times when the NYSE is closed or during emergency circumstances, as determined by the SEC.

Exchanging Shares

An exchange occurs when you use the proceeds from the redemption of shares of one Vanguard fund to simultaneously purchase shares of a different Vanguard fund. You can make exchange requests online (if you are registered for online access), by telephone, or by mail. See Purchasing Shares and Redeeming Shares.

If the NYSE is open for regular trading (generally until 4 p.m., Eastern time, on a business day) at the time an exchange request is received in good order, the trade date generally will be the same day. See Other Rules You Should Know—Good Order for additional information on all transaction requests.

Vanguard will not accept your request to cancel any exchange request once processing has begun. Please be careful when placing an exchange request.

Call Vanguard before attempting to exchange a large dollar amount. By calling us before you attempt to exchange a large dollar amount, you may avoid delayed or rejected transactions.

Please note that Vanguard reserves the right, without notice, to revise or terminate the exchange privilege, limit the amount of any exchange, or reject an exchange, at any time, for any reason. See Frequent-Trading Limitations for additional restrictions on exchanges.

Frequent-Trading Limitations

Because excessive transactions can disrupt management of a fund and increase the fund’s costs for all shareholders, the board of trustees of each Vanguard fund places certain limits on frequent trading in the funds. Each Vanguard fund (other than money market funds and short-term bond funds, but including Vanguard Short-Term Inflation-Protected Securities Index Fund) limits an investor’s purchases or exchanges into a fund account for 30 calendar days after the investor has redeemed or exchanged out of that fund account. ETF Shares are not subject to these frequent-trading limits.

For Vanguard Retirement Investment Program pooled plans, the limitations apply to exchanges made online or by telephone.

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These frequent-trading limitations do not apply to the following:

• Purchases of shares with reinvested dividend or capital gains distributions.

• Transactions through Vanguard’s Automatic Investment Plan, Automatic Exchange Service, Direct Deposit Service, Automatic Withdrawal Plan, Required Minimum Distribution Service, and Vanguard Small Business Online^®.

• Discretionary transactions through Vanguard Asset Management Services^™, Vanguard Personal Advisor Services^®, and Vanguard Institutional Advisory Services^®.

• Redemptions of shares to pay fund or account fees.

• Redemptions of shares to remove excess shareholder contributions to certain types of retirement accounts (including, but not limited to, IRAs, certain Individual 403(b)(7) Custodial Accounts, and Vanguard Individual 401(k) Plans).

• Transfers and reregistrations of shares within the same fund.

• Purchases of shares by asset transfer or direct rollover.

• Conversions of shares from one share class to another in the same fund.

• Checkwriting redemptions.

• Section 529 college savings plans.

• Certain approved institutional portfolios and asset allocation programs, as well as trades made by funds or trusts managed by Vanguard or its affiliates that invest in other Vanguard funds. (Please note that shareholders of Vanguard’s funds of funds are subject to the limitations.)

For participants in employer-sponsored defined contribution plans,* the frequent-trading limitations do not apply to:

• Purchases of shares with participant payroll or employer contributions or loan repayments.

• Purchases of shares with reinvested dividend or capital gains distributions.

• Distributions, loans, and in-service withdrawals from a plan.

• Redemptions of shares as part of a plan termination or at the direction of the plan.

• Transactions executed through the Vanguard Managed Account Program.

• Redemptions of shares to pay fund or account fees.

• Share or asset transfers or rollovers.

• Reregistrations of shares.

• Conversions of shares from one share class to another in the same fund.

• Exchange requests submitted by written request to Vanguard. (Exchange requests submitted by fax, if otherwise permitted, are subject to the limitations.)

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* The following Vanguard fund accounts are subject to the frequent-trading limitations: SEP-IRAs, SIMPLE IRAs, certain Individual 403(b)(7) Custodial Accounts, and Vanguard Individual 401(k) Plans.

Accounts Held by Institutions (Other Than Defined Contribution Plans)

Vanguard will systematically monitor for frequent trading in institutional clients’ accounts. If we detect suspicious trading activity, we will investigate and take appropriate action, which may include applying to a client’s accounts the 30-day policy previously described, prohibiting a client’s purchases of fund shares, and/or revoking the client’s exchange privilege.

Accounts Held by Intermediaries

When intermediaries establish accounts in Vanguard funds for the benefit of their clients, we cannot always monitor the trading activity of the individual clients. However, we review trading activity at the intermediary (omnibus) level, and if we detect suspicious activity, we will investigate and take appropriate action. If necessary, Vanguard may prohibit additional purchases of fund shares by an intermediary, including for the benefit of certain of the intermediary’s clients. Intermediaries also may monitor their clients’ trading activities with respect to Vanguard funds.

For those Vanguard funds that charge purchase and/or redemption fees, intermediaries will be asked to assess these fees on client accounts and remit these fees to the funds. The application of purchase and redemption fees and frequent-trading limitations may vary among intermediaries. There are no assurances that Vanguard will successfully identify all intermediaries or that intermediaries will properly assess purchase and redemption fees or administer frequent-trading limitations. If you invest with Vanguard through an intermediary, please read that firm’s materials carefully to learn of any other rules or fees that may apply.

Other Rules You Should Know

Prospectus and Shareholder Report Mailings

When two or more shareholders have the same last name and address, just one summary prospectus (or prospectus) and/or shareholder report may be sent in an attempt to eliminate the unnecessary expense of duplicate mailings. You may request individual prospectuses and reports by contacting our Client Services Department in writing, by telephone, or online. See Contacting Vanguard.

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Vanguard.com

Registration. If you are a registered user of vanguard.com, you can review your account holdings; buy, sell, or exchange shares of most Vanguard funds; and perform most other transactions through our website. You must register for this service online.

Electronic delivery. Vanguard can deliver your account statements, transaction confirmations, prospectuses, certain tax forms, and shareholder reports electronically. If you are a registered user of vanguard.com, you can consent to the electronic delivery of these documents by logging on and changing your mailing preferences under “Account Maintenance.” You can revoke your electronic consent at any time through our website, and we will begin to send paper copies of these documents within 30 days of receiving your revocation.

Telephone Transactions

Automatic. When we set up your account, we will automatically enable you to do business with us by telephone, unless you instruct us otherwise in writing.

Tele-Account^®. To obtain fund and account information through Vanguard’s automated telephone service, you must first establish a Personal Identification Number (PIN) by calling Tele-Account at 800-662-6273.

Proof of a caller’s authority. We reserve the right to refuse a telephone request if the caller is unable to provide the requested information or if we reasonably believe that the caller is not an individual authorized to act on the account. Before we allow a caller to act on an account, we may request the following information:

• Authorization to act on the account (as the account owner or by legal documentation or other means).

• Account registration and address.

• Fund name and account number, if applicable.

• Other information relating to the caller, the account owner, or the account.

Good Order

We reserve the right to reject any transaction instructions that are not in “good order.” Good order generally means that your instructions:

• Are provided by the person(s) authorized in accordance with Vanguard’s policies and procedures to access the account and request transactions.

• Include the fund name and account number.

• Include the amount of the transaction (stated in dollars, shares, or percentage).

Written instructions also must generally include:

• An original signature and date from the authorized person(s).

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• Signature guarantees or notarized signatures, if required for the type of transaction.

(Call Vanguard for specific requirements.)

• Any supporting documentation that may be required.

Written instructions may be acceptable when a Vanguard form is not applicable. The requirements vary among types of accounts and transactions. For more information, consult our website at vanguard.com or see Contacting Vanguard.

Vanguard reserves the right, without notice, to revise the requirements for good order.

Future Trade-Date Requests

Vanguard does not accept requests to hold a purchase, conversion, redemption, or exchange transaction for a future date. All such requests will receive trade dates as previously described in Purchasing Shares, Converting Shares, Redeeming Shares, and

Exchanging Shares. Vanguard reserves the right to return future-dated purchase checks.

Accounts With More Than One Owner

If an account has more than one owner or authorized person, Vanguard generally will accept instructions from any one owner or authorized person.

Responsibility for Fraud

Vanguard will not be responsible for any account losses because of fraud if we reasonably believe that the person transacting business on an account is authorized to do so. Please take precautions to protect yourself from fraud. Keep your account information private, and immediately review any account statements or other information that we provide to you. It is important that you contact Vanguard immediately about any transactions or changes to your account that you believe to be unauthorized.

Uncashed Checks

Please cash your distribution or redemption checks promptly. Vanguard will not pay interest on uncashed checks. Vanguard may be required to transfer assets related to uncashed checks to a state under the state’s abandoned property law.

Dormant Accounts

If your account has no activity in it for a period of time, Vanguard may be required to transfer it to a state under the state’s abandoned property law.

Unusual Circumstances

If you experience difficulty contacting Vanguard online or by telephone, you can send us your transaction request by regular or express mail. See Contacting Vanguard for addresses.

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Investing With Vanguard Through Other Firms

You may purchase or sell shares of most Vanguard funds through a financial intermediary, such as a bank, a broker, or an investment advisor. Please consult your financial intermediary to determine which, if any, shares are available through that firm and to learn about other rules that may apply. Your financial intermediary can provide you with account information and any required tax forms.

Please see Frequent-Trading Limitations—Accounts Held by Intermediaries for information about the assessment of any purchase or redemption fees and the monitoring of frequent trading for accounts held by intermediaries.

Low-Balance Accounts

The Fund reserves the right to convert an investor’s Institutional Plus Shares to Institutional Shares of the Fund if the investor’s fund account balance falls below the account minimum for any reason, including market fluctuation. In addition, the Fund reserves the right to liquidate an investor’s Institutional Shares if the investor’s fund account balance falls below the account minimum for that share class for any reason, including market fluctuation. This liquidation policy applies to nonretirement fund accounts and accounts that are held through intermediaries. Any such conversion or liquidation will be preceded by written notice to the investor.

Right to Change Policies

In addition to the rights expressly stated elsewhere in this prospectus, Vanguard reserves the right, without notice, to (1) alter, add, or discontinue any conditions of purchase (including eligibility requirements), redemption, exchange, conversion, service, or privilege at any time; (2) accept initial purchases by telephone; (3) freeze any account and/or suspend account services if Vanguard has received reasonable notice of a dispute regarding the assets in an account, including notice of a dispute between the registered or beneficial account owners, or if Vanguard reasonably believes a fraudulent transaction may occur or has occurred; (4) temporarily freeze any account and/or suspend account services upon initial notification to Vanguard of the death of the shareholder until Vanguard receives required documentation in good order; (5) alter, impose, discontinue, or waive any purchase fee, redemption fee, account service fee, or other fees charged to a shareholder or a group of shareholders; and (6) redeem an account or suspend account privileges, without the owner’s permission to do so, in cases of threatening conduct or activity Vanguard believes to be suspicious, fraudulent, or illegal. Changes may affect any or all investors. These actions will be taken when, at the sole discretion of Vanguard management, Vanguard reasonably believes they are in the best interest of a fund.

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Share Classes

Vanguard reserves the right, without notice, to change the eligibility requirements of its share classes, including the types of clients who are eligible to purchase each share class.

Fund and Account Updates

Confirmation Statements

We will send (or provide through our website, whichever you prefer) a confirmation of your trade date and the amount of your transaction when you buy, sell, exchange, or convert shares. However, we will not send confirmations reflecting only checkwriting redemptions or the reinvestment of dividend or capital gains distributions. For any month in which you had a checkwriting redemption, a Checkwriting Activity Statement will be sent to you itemizing the checkwriting redemptions for that month. Promptly review each confirmation statement that we provide to you. It is important that you contact Vanguard immediately with any questions you may have about any transaction reflected on a confirmation statement, or Vanguard will consider the transaction properly processed.

Portfolio Summaries

We will send (or provide through our website, whichever you prefer) quarterly portfolio summaries to help you keep track of your accounts throughout the year. If you prefer, you may request to receive monthly portfolio summaries. Each summary shows the market value of your account at the close of the statement period, as well as all distributions, purchases, redemptions, exchanges, transfers, and conversions for the current calendar quarter (or month). Promptly review each summary that we provide to you. It is important that you contact Vanguard immediately with any questions you may have about any transaction reflected on the summary, or Vanguard will consider the transaction properly processed.

Tax Information Statements

For most accounts, Vanguard (or your intermediary) is required to provide annual tax forms to assist you in preparing your income tax returns. These forms are generally available for each calendar year early in the following year. Registered users of vanguard.com can also view certain forms through our website. Vanguard (or your intermediary) may also provide you with additional tax-related documentation. For more information, consult our website at vanguard.com or see Contacting Vanguard.

Annual and Semiannual Reports

We will send (or provide through our website, whichever you prefer) reports about Vanguard Institutional Total Stock Market Index Fund twice a year, in February and

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August. These reports include overviews of the financial markets and provide the following specific Fund information:

• Performance assessments and comparisons with industry benchmarks.

• Financial statements with listings of Fund holdings.

Portfolio Holdings

Please consult the Fund‘s Statement of Additional Information or our website for a description of the policies and procedures that govern disclosure of the Fund’s portfolio holdings.

Employer-Sponsored Plans

Your plan administrator or your employee benefits office can provide you with detailed information on how to participate in your plan and how to elect the Fund as an investment option.

• If you have any questions about the Fund or Vanguard, including those about the Fund’s investment objective, strategies, or risks, contact Vanguard Participant Services toll-free at 800-523-1188 or visit our website at vanguard.com.

• If you have questions about your account, contact your plan administrator or the organization that provides recordkeeping services for your plan.

• Be sure to carefully read each topic that pertains to your transactions with Vanguard.

Vanguard reserves the right to change its policies without notice to shareholders.

Transactions

Processing times for your transaction requests may differ among recordkeepers or among transaction and funding types. Your plan’s recordkeeper (which may also be Vanguard) will determine the necessary processing time frames for your transaction requests prior to submission to the Fund. Consult your recordkeeper or plan administrator for more information.

If Vanguard is serving as your plan recordkeeper and if your transaction involves one or more investments with an early cut-off time for processing or another trading restriction, your entire transaction will be subject to the restriction when the trade date for your transaction is determined.

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Vanguard Addresses

Please be sure to use the correct address. Use of an incorrect address could delay the processing of your transaction.

Vanguard funds are not sponsored, endorsed, sold, or promoted by the University of Chicago or its Center for Research in Security Prices, and neither the University of Chicago nor its Center for Research in Security Prices makes any representation regarding the advisability of investing in the funds.

39

Glossary of Investment Terms

Active Management. An investment approach that seeks to exceed the average returns of a particular financial market or market segment. In selecting securities to buy and sell, active managers may rely on, among other things, research, market forecasts, quantitative models, and their own judgment and experience.

Capital Gains Distribution. Payment to mutual fund shareholders of gains realized on securities that a fund has sold at a profit, minus any realized losses.

Common Stock. A security representing ownership rights in a corporation.

Dividend Distribution. Payment to mutual fund shareholders of income from interest or dividends generated by a fund’s investments.

Expense Ratio. A fund’s total annual operating expenses expressed as a percentage of the fund’s average net assets. The expense ratio includes management and administrative expenses, but it does not include the transaction costs of buying and selling portfolio securities.

Inception Date. The date on which the assets of a fund (or one of its share classes) are first invested in accordance with the fund’s investment objective. For funds with a subscription period, the inception date is the day after that period ends. Investment performance is generally measured from the inception date.

Indexing. A low-cost investment strategy in which a mutual fund attempts to track—rather than outperform—a specified market benchmark, or “index.”

Joint Committed Credit Facility. The Fund participates, along with other funds managed by Vanguard, in a committed credit facility provided by a syndicate of lenders pursuant to a credit agreement that may be renewed annually; each fund is individually liable for its borrowings, if any, under the credit facility. The amount and terms of the committed credit facility are subject to approval by the fund’s board of trustees and renegotiation with the lender syndicate on an annual basis.

Median Market Capitalization. An indicator of the size of companies in which a fund invests; the midpoint of market capitalization (market price x shares outstanding) of a fund’s stocks, weighted by the proportion of the fund’s assets invested in each stock. Stocks representing half of the fund’s assets have market capitalizations above the median, and the rest are below it.

MSCI US Broad Market Index. An index that tracks virtually all stocks that trade in the U.S. stock market.

Mutual Fund. An investment company that pools the money of many people and invests it in a variety of securities in an effort to achieve a specific objective over time.

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New York Stock Exchange (NYSE). A stock exchange based in New York City that is open for regular trading on business days, Monday through Friday, from 9:30 a.m. to 4 p.m., Eastern time. Net asset values (NAVs) are calculated each business day as of the close of regular trading on the NYSE.

Price/Earnings (P/E) Ratio. The current share price of a stock, divided by its per-share earnings (profits). A stock selling for $20, with earnings of $2 per share, has a price/earnings ratio of 10.

Securities. Stocks, bonds, money market instruments, and other investments.

Spliced Institutional Total Stock Market Index. An index that reflects performance of the MSCI US Broad Market Index through January 14, 2013, and the CRSP US Total Market Index thereafter.

Total Return. A percentage change, over a specified time period, in a mutual fund’s net asset value, assuming the reinvestment of all distributions of dividends and capital gains.

Volatility. The fluctuations in value of a mutual fund or other security. The greater a fund’s volatility, the wider the fluctuations in its returns.

Yield. Income (interest or dividends) earned by an investment, expressed as a percentage of the investment’s price.

Institutional Division P.O. Box 2900 Valley Forge, PA 19482-2900

Connect with Vanguard^® > vanguard.com

For More Information

If you would like more information about Vanguard Institutional Total Stock Market Index Fund, the following documents are available free upon request:

Annual/Semiannual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semiannual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Statement of Additional Information (SAI)

The SAI provides more detailed information about the Fund and is incorporated by reference into (and thus legally a part of) this prospectus.

To receive a free copy of the latest annual or semiannual report or the SAI, or to request additional information about the Fund or other Vanguard funds, please visit vanguard.com or contact us as follows:

If you are an individual investor:

The Vanguard Group

Investor Information Department P.O. Box 2900 Valley Forge, PA 19482-2900

Telephone: 800-662-7447; Text telephone for people with hearing impairment: 800-749-7273

If you are a client of Vanguard’s Institutional Division:

The Vanguard Group

Institutional Investor Information Department P.O. Box 2900 Valley Forge, PA 19482-2900 Telephone: 888-809-8102; Text telephone for people with hearing impairment: 800-749-7273

If you are a current Vanguard shareholder and would like information about your account, account transactions, and/or account statements, please call:

Client Services Department

Telephone: 800-662-2739; Text telephone for people with hearing impairment: 800-749-7273

Information Provided by the Securities and Exchange Commission (SEC)

You can review and copy information about the Fund (including the SAI) at the SEC’s Public Reference Room in Washington, DC. To find out more about this public service, call the SEC at 202-551-8090. Reports and other information about the Fund are also available in the EDGAR database on the SEC’s website at www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following email address: [email protected], or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

Fund’s Investment Company Act file number: 811-06093

© 2018 The Vanguard Group, Inc. All rights reserved. Vanguard Marketing Corporation, Distributor.

I 871 042018

PART B

VANGUARD^® INSTITUTIONAL INDEX FUNDS

STATEMENT OF ADDITIONAL INFORMATION

April 26, 2018

This Statement of Additional Information is not a prospectus but should be read in conjunction with a Fund’s current prospectus (dated April 26, 2018). To obtain, without charge, a prospectus or the most recent Annual Report to Shareholders, which contains the Fund’s financial statements as hereby incorporated by reference, please contact The Vanguard Group, Inc. (Vanguard).

Phone: Institutional Investor Information Department at 888-809-8102 Online: vanguard.com

DESCRIPTION OF THE TRUST

Vanguard Institutional Index Funds (the Trust) currently offers the following funds and share classes (identified by ticker symbol):

The Trust has the ability to offer additional funds or classes of shares. There is no limit on the number of full and fractional shares that may be issued for a single fund or class of shares.

Organization

The Trust was organized as a Pennsylvania business trust in 1990 and was reorganized as a Delaware statutory trust in 1998. The Trust is registered with the United States Securities and Exchange Commission (SEC) under the Investment Company Act of 1940 (the 1940 Act) as an open-end management investment company. The Funds are classified as diversified within the meaning of the 1940 Act.

Service Providers

Custodians. State Street Bank and Trust Company, One Lincoln Street, Boston, MA 02111 (for the Institutional Index Fund) and Brown Brothers Harriman & Co., 50 Post Office Square, Boston, MA 02110 (for the Institutional Total Stock

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Market Index Fund), serve as the Funds’ custodians. The custodians are responsible for maintaining the Funds’ assets, keeping all necessary accounts and records of Fund assets, and appointing any foreign subcustodians or foreign securities depositories.

Independent Registered Public Accounting Firm. Pricewaterhouse Coopers LLP, Two Commerce Square, Suite 1800, 2001 Market Street, Philadelphia, PA 19103-7042, serves as the Funds‘ independent registered public accounting firm. The independent registered public accounting firm audits the Funds‘ annual financial statements and provides other related services.

Transfer and Dividend-Paying Agent. The Funds‘ transfer agent and dividend-paying agent is Vanguard, P.O. Box 2600, Valley Forge, PA 19482.

Characteristics of the Funds‘ Shares

Restrictions on Holding or Disposing of Shares. There are no restrictions on the right of shareholders to retain or dispose of a Fund’s shares, other than those described in the Fund’s current prospectus and elsewhere in this Statement of Additional Information. Each Fund or class may be terminated by reorganization into another mutual fund or class or by liquidation and distribution of the assets of the Fund or class. Unless terminated by reorganization or liquidation, each Fund and share class will continue indefinitely.

Shareholder Liability. The Trust is organized under Delaware law, which provides that shareholders of a statutory trust are entitled to the same limitations of personal liability as shareholders of a corporation organized under Delaware law. This means that a shareholder of a Fund generally will not be personally liable for payment of the Fund’s debts. Some state courts, however, may not apply Delaware law on this point. We believe that the possibility of such a situation arising is remote.

Dividend Rights. The shareholders of each class of a Fund are entitled to receive any dividends or other distributions declared by the Fund for each such class. No shares of a Fund have priority or preference over any other shares of the Fund with respect to distributions. Distributions will be made from the assets of the Fund and will be paid ratably to all shareholders of a particular class according to the number of shares of the class held by shareholders on the record date. The amount of dividends per share may vary between separate share classes of the Fund based upon differences in the net asset values of the different classes and differences in the way that expenses are allocated between share classes pursuant to a multiple class plan approved by the Fund’s board of trustees.

Voting Rights. Shareholders are entitled to vote on a matter if (1) the matter concerns an amendment to the Declaration of Trust that would adversely affect to a material degree the rights and preferences of the shares of a Fund or any class; (2) the trustees determine that it is necessary or desirable to obtain a shareholder vote; (3) a merger or consolidation, share conversion, share exchange, or sale of assets is proposed and a shareholder vote is required by the 1940 Act to approve the transaction; or (4) a shareholder vote is required under the 1940 Act. The 1940 Act requires a shareholder vote under various circumstances, including to elect or remove trustees upon the written request of shareholders representing 10% or more of a Fund’s net assets, to change any fundamental policy of a Fund (please see Fundamental Policies), and to enter into certain merger transactions. Unless otherwise required by applicable law, shareholders of a Fund receive one vote for each dollar of net asset value owned on the record date and a fractional vote for each fractional dollar of net asset value owned on the record date. However, only the shares of the Fund or class affected by a particular matter are entitled to vote on that matter. In addition, each class has exclusive voting rights on any matter submitted to shareholders that relates solely to that class, and each class has separate voting rights on any matter submitted to shareholders in which the interests of one class differ from the interests of another. Voting rights are noncumulative and cannot be modified without a majority vote by the shareholders.

Liquidation Rights. In the event that a Fund is liquidated, shareholders will be entitled to receive a pro rata share of the Fund’s net assets. In the event that a class of shares is liquidated, shareholders of that class will be entitled to receive a pro rata share of the Fund’s net assets that are allocated to that class. Shareholders may receive cash, securities, or a combination of the two.

Preemptive Rights. There are no preemptive rights associated with the Funds‘ shares.

Conversion Rights. Shareholders of each Fund may convert their shares into another class of shares of the same Fund upon the satisfaction of any then-applicable eligibility requirements as described in the Fund’s current prospectus.

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Redemption Provisions. Each Fund’s redemption provisions are described in its current prospectus and elsewhere in this Statement of Additional Information.

Sinking Fund Provisions. The Funds have no sinking fund provisions.

Calls or Assessment. Each Fund’s shares, when issued, are fully paid and non-assessable.

Tax Status of the Funds

Each Fund expects to qualify each year for treatment as a “regulated investment company” under Subchapter M of the Internal Revenue Code of 1986, as amended (the IRC). This special tax status means that the Fund will not be liable for federal tax on income and capital gains distributed to shareholders. In order to preserve its tax status, the Fund must comply with certain requirements relating to the source of its income and the diversification of its assets. If a Fund fails to meet these requirements in any taxable year, the Fund will, in some cases, be able to cure such failure, including by paying a fund-level tax, paying interest, making additional distributions, and/or disposing of certain assets. If the Funds is ineligible to or otherwise does not cure such failure for any year, it will be subject to tax on its taxable income at corporate rates, and all distributions from earnings and profits, including any distributions of net tax-exempt income and net long-term capital gains, will be taxable to shareholders as ordinary income. In addition, the Fund could be required to recognize unrealized gains, pay substantial taxes and interest, and make substantial distributions before regaining its tax status as a regulated investment company.

Dividends received and distributed by the Fund on shares of stock of domestic corporations (excluding REITs) and certain foreign corporations generally may be eligible to be reported by the Fund, and treated by individual shareholders, as “qualified dividend income” taxed at long-term capital gain rates instead of at higher ordinary income tax rates. Individuals must satisfy holding period and other requirements in order to be eligible for such treatment. Capital gains distributed by the Fund are not eligible for treatment as qualified dividend income.

Under recent tax legislation, individuals (and certain other noncorporate entities) are generally eligible for a 20% deduction with respect to taxable ordinary dividends from REITs and certain taxable income from publicly traded partnerships. Currently, there is not a regulatory mechanism for regulated investment companies to pass through the 20% deduction to shareholders. As a result, in comparison, investors investing directly in REITs or publicly traded partnerships would generally be eligible for the 20% deduction for such taxable income from these investments while investors investing in REITs or publicly traded partnerships indirectly through a Fund would not be eligible for the 20% deduction for their share of such taxable income.

Dividends received and distributed by the Fund on shares of stock of domestic corporations (excluding REITs) may be eligible for the dividends-received deduction applicable to corporate shareholders. Corporations must satisfy certain requirements in order to claim the deduction. Capital gains distributed by the Fund are not eligible for the dividends-received deduction.

Each Fund may declare a capital gain dividend consisting of the excess (if any) of net realized long-term capital gains over net realized short-term capital losses. Net capital gains for a fiscal year are computed by taking into account any capital loss carryforwards of the Fund. For Fund fiscal years beginning on or after December 22, 2010, capital losses may be carried forward indefinitely and retain their character as either short-term or long-term. Under prior law, net capital losses could be carried forward for eight tax years and were treated as short-term capital losses. A Fund is required to use capital losses arising in fiscal years beginning on or after December 22, 2010, before using capital losses arising in fiscal years beginning prior to December 22, 2010.

FUNDAMENTAL POLICIES

Each Fund is subject to the following fundamental investment policies, which cannot be changed in any material way without the approval of the holders of a majority of the Fund’s shares. For these purposes, a “majority” of shares means shares representing the lesser of (1) 67% or more of the Fund’s net assets voted, so long as shares representing more than 50% of the Fund’s net assets are present or represented by proxy or (2) more than 50% of the Fund’s net assets.

Borrowing. Each Fund may borrow money only as permitted by the 1940 Act or other governing statute, by the Rules thereunder, or by the SEC or other regulatory agency with authority over the Fund.

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Commodities. Each Fund may invest in commodities only as permitted by the 1940 Act or other governing statute, by the Rules thereunder, or by the SEC or other regulatory agency with authority over the Fund.

Diversification. With respect to 75% of its total assets, each Fund may not (1) purchase more than 10% of the outstanding voting securities of any one issuer or (2) purchase securities of any issuer if, as a result, more than 5% of the Fund’s total assets would be invested in that issuer’s securities. This limitation does not apply to obligations of the U.S. government or its agencies or instrumentalities.

Industry Concentration. Each Fund will not concentrate its investments in the securities of issuers whose principal business activities are in the same industry, except as may be necessary to approximate the composition of its target index.

Investment Objective. The investment objective of each Fund may not be materially changed without a shareholder vote.

Loans. Each Fund may make loans to another person only as permitted by the 1940 Act or other governing statute, by the Rules thereunder, or by the SEC or other regulatory agency with authority over the Fund.

Real Estate. Each Fund may not invest directly in real estate unless it is acquired as a result of ownership of securities or other instruments. This restriction shall not prevent the Fund from investing in securities or other instruments (1) issued by companies that invest, deal, or otherwise engage in transactions in real estate or (2) backed or secured by real estate or interests in real estate.

Senior Securities. Each Fund may not issue senior securities except as permitted by the 1940 Act or other governing statute, by the Rules thereunder, or by the SEC or other regulatory agency with authority over the Fund.

Underwriting. Each Fund may not act as an underwriter of another issuer’s securities, except to the extent that the Fund may be deemed to be an underwriter within the meaning of the Securities Act of 1933 (the 1933 Act), in connection with the purchase and sale of portfolio securities.

Compliance with the fundamental policies previously described is generally measured at the time the securities are purchased. Unless otherwise required by the 1940 Act (as is the case with borrowing), if a percentage restriction is adhered to at the time the investment is made, a later change in percentage resulting from a change in the market value of assets will not constitute a violation of such restriction. All fundamental policies must comply with applicable regulatory requirements. For more details, see Investment Strategies, Risks, and Nonfundamental Policies.

INVESTMENT STRATEGIES, RISKS, AND NONFUNDAMENTAL POLICIES

Some of the investment strategies and policies described on the following pages and in each Fund’s prospectus set forth percentage limitations on a Fund’s investment in, or holdings of, certain securities or other assets. Unless otherwise required by law, compliance with these strategies and policies will be determined immediately after the acquisition of such securities or assets by the Fund. Subsequent changes in values, net assets, or other circumstances will not be considered when determining whether the investment complies with the Fund’s investment strategies and policies.

The following investment strategies, risks, and policies supplement each Fund’s investment strategies, risks, and policies set forth in the prospectus. With respect to the different investments discussed as follows, a Fund may acquire such investments to the extent consistent with its investment strategies and policies.

Borrowing. A fund’s ability to borrow money is limited by its investment policies and limitations; by the 1940 Act; and by applicable exemptions, no-action letters, interpretations, and other pronouncements issued from time to time by the SEC and its staff or any other regulatory authority with jurisdiction. Under the 1940 Act, a fund is required to maintain continuous asset coverage (that is, total assets including borrowings, less liabilities exclusive of borrowings) of 300% of the amount borrowed, with an exception for borrowings not in excess of 5% of the fund’s total assets made for temporary or emergency purposes. Any borrowings for temporary purposes in excess of 5% of the fund’s total assets must maintain continuous asset coverage. If the 300% asset coverage should decline as a result of market fluctuations or for other reasons, a fund may be required to sell some of its portfolio holdings within three days (excluding Sundays and holidays) to reduce the debt and restore the 300% asset coverage, even though it may be disadvantageous from an investment standpoint to sell securities at that time.

Borrowing will tend to exaggerate the effect on net asset value of any increase or decrease in the market value of a fund’s portfolio. Money borrowed will be subject to interest costs that may or may not be recovered by earnings on the securities purchased with the proceeds of such borrowing. A fund also may be required to maintain minimum average

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balances in connection with a borrowing or to pay a commitment or other fee to maintain a line of credit; either of these requirements would increase the cost of borrowing over the stated interest rate.

The SEC takes the position that transactions that have a leveraging effect on the capital structure of a fund or are economically equivalent to borrowing can be viewed as constituting a form of borrowing by the fund for purposes of the 1940 Act. These transactions can include entering into reverse repurchase agreements; engaging in mortgage-dollar-roll transactions; selling securities short (other than short sales “against-the-box”); buying and selling certain derivatives (such as futures contracts); selling (or writing) put and call options; engaging in sale-buybacks; entering into firm-commitment and standby-commitment agreements; engaging in when-issued, delayed-delivery, or forward-commitment transactions; and participating in other similar trading practices. (Additional discussion about a number of these transactions can be found on the following pages.) A borrowing transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund maintains an offsetting financial position; segregates liquid assets (with such liquidity determined by the advisor in accordance with procedures established by the board of trustees) equal (as determined on a daily mark-to-market basis) in value to the fund’s potential economic exposure under the borrowing transaction; or otherwise “covers” the transaction in accordance with applicable SEC guidance (collectively, “covers” the transaction). A fund may have to buy or sell a security at a disadvantageous time or price in order to cover a borrowing transaction. In addition, segregated assets may not be available to satisfy redemptions or to fulfill other obligations.

Common Stock. Common stock represents an equity or ownership interest in an issuer. Common stock typically entitles the owner to vote on the election of directors and other important matters, as well as to receive dividends on such stock. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of bonds, other debt holders, and owners of preferred stock take precedence over the claims of those who own common stock.

Convertible Securities. Convertible securities are hybrid securities that combine the investment characteristics of bonds and common stocks. Convertible securities typically consist of debt securities or preferred stock that may be converted (on a voluntary or mandatory basis) within a specified period of time (normally for the entire life of the security) into a certain amount of common stock or other equity security of the same or a different issuer at a predetermined price. Convertible securities also include debt securities with warrants or common stock attached and derivatives combining the features of debt securities and equity securities. Other convertible securities with features and risks not specifically referred to herein may become available in the future. Convertible securities involve risks similar to those of both fixed income and equity securities. In a corporation’s capital structure, convertible securities are senior to common stock but are usually subordinated to senior debt obligations of the issuer.

The market value of a convertible security is a function of its “investment value” and its “conversion value.” A security’s “investment value” represents the value of the security without its conversion feature (i.e., a nonconvertible debt security). The investment value may be determined by reference to its credit quality and the current value of its yield to maturity or probable call date. At any given time, investment value is dependent upon such factors as the general level of interest rates, the yield of similar nonconvertible securities, the financial strength of the issuer, and the seniority of the security in the issuer’s capital structure. A security’s “conversion value” is determined by multiplying the number of shares the holder is entitled to receive upon conversion or exchange by the current price of the underlying security. If the conversion value of a convertible security is significantly below its investment value, the convertible security will trade like nonconvertible debt or preferred stock and its market value will not be influenced greatly by fluctuations in the market price of the underlying security. In that circumstance, the convertible security takes on the characteristics of a bond, and its price moves in the opposite direction from interest rates. Conversely, if the conversion value of a convertible security is near or above its investment value, the market value of the convertible security will be more heavily influenced by fluctuations in the market price of the underlying security. In that case, the convertible security’s price may be as volatile as that of common stock. Because both interest rates and market movements can influence its value, a convertible security generally is not as sensitive to interest rates as a similar debt security, nor is it as sensitive to changes in share price as its underlying equity security. Convertible securities are often rated below investment-grade or are not rated, and they are generally subject to a high degree of credit risk.

Although all markets are prone to change over time, the generally high rate at which convertible securities are retired (through mandatory or scheduled conversions by issuers or through voluntary redemptions by holders) and replaced with newly issued convertible securities may cause the convertible securities market to change more rapidly than other markets. For example, a concentration of available convertible securities in a few economic sectors could elevate the

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sensitivity of the convertible securities market to the volatility of the equity markets and to the specific risks of those sectors. Moreover, convertible securities with innovative structures, such as mandatory-conversion securities and equity-linked securities, have increased the sensitivity of the convertible securities market to the volatility of the equity markets and to the special risks of those innovations, which may include risks different from, and possibly greater than, those associated with traditional convertible securities. A convertible security may be subject to redemption at the option of the issuer at a price set in the governing instrument of the convertible security. If a convertible security held by a fund is subject to such redemption option and is called for redemption, the fund must allow the issuer to redeem the security, convert it into the underlying common stock, or sell the security to a third party.

Cybersecurity Risks. The increased use of technology to conduct business could subject a fund and its third-party service providers (including, but not limited to, investment advisors and custodians) to risks associated with cybersecurity. In general, a cybersecurity incident can occur as a result of a deliberate attack designed to gain unauthorized access to digital systems. If the attack is successful, an unauthorized person or persons could misappropriate assets or sensitive information, corrupt data, or cause operational disruption. A cybersecurity incident could also occur unintentionally if, for example, an authorized person inadvertently released proprietary or confidential information. Vanguard has developed robust technological safeguards and business continuity plans to prevent, or reduce the impact of, potential cybersecurity incidents. Additionally, Vanguard has a process for assessing the information security and/or cybersecurity programs implemented by a fund’s third-party service providers, which helps minimize the risk of potential incidents. Despite these measures, a cybersecurity incident still has the potential to disrupt business operations, which could negatively impact a fund and/or its shareholders. Some examples of negative impacts that could occur as a result of a cybersecurity incident include, but are not limited to, the following: a fund may be unable to calculate its net asset value (NAV), a fund’s shareholders may be unable to transact business, a fund may be unable to process transactions on behalf of its shareholders, or a fund may be unable to safeguard its data or the personal information of its shareholders.

Depositary Receipts. Depositary receipts (also sold as participatory notes) are securities that evidence ownership interests in a security or a pool of securities that have been deposited with a “depository.” Depositary receipts may be sponsored or unsponsored and include American Depositary Receipts (ADRs), European Depositary Receipts (EDRs), and Global Depositary Receipts (GDRs). For ADRs, the depository is typically a U.S. financial institution, and the underlying securities are issued by a foreign issuer. For other depositary receipts, the depository may be a foreign or a U.S. entity, and the underlying securities may have a foreign or a U.S. issuer. Depositary receipts will not necessarily be denominated in the same currency as their underlying securities. Generally, ADRs are issued in registered form, denominated in U.S. dollars, and designed for use in the U.S. securities markets. Other depositary receipts, such as GDRs and EDRs, may be issued in bearer form and denominated in other currencies, and they are generally designed for use in securities markets outside the United States. Although the two types of depositary receipt facilities (sponsored and unsponsored) are similar, there are differences regarding a holder’s rights and obligations and the practices of market participants.

A depository may establish an unsponsored facility without participation by (or acquiescence of) the underlying issuer; typically, however, the depository requests a letter of nonobjection from the underlying issuer prior to establishing the facility. Holders of unsponsored depositary receipts generally bear all the costs of the facility. The depository usually charges fees upon the deposit and withdrawal of the underlying securities, the conversion of dividends into U.S. dollars or other currency, the disposition of noncash distributions, and the performance of other services. The depository of an unsponsored facility frequently is under no obligation to distribute shareholder communications received from the underlying issuer or to pass through voting rights to depositary receipt holders with respect to the underlying securities.

Sponsored depositary receipt facilities are created in generally the same manner as unsponsored facilities, except that sponsored depositary receipts are established jointly by a depository and the underlying issuer through a deposit agreement. The deposit agreement sets out the rights and responsibilities of the underlying issuer, the depository, and the depositary receipt holders. With sponsored facilities, the underlying issuer typically bears some of the costs of the depositary receipts (such as dividend payment fees of the depository), although most sponsored depositary receipt holders may bear costs such as deposit and withdrawal fees. Depositories of most sponsored depositary receipts agree to distribute notices of shareholder meetings, voting instructions, and other shareholder communications and information to the depositary receipt holders at the underlying issuer’s request.

For purposes of a fund’s investment policies, investments in depositary receipts will be deemed to be investments in the underlying securities. Thus, a depositary receipt representing ownership of common stock will be treated as common

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stock. Depositary receipts do not eliminate all of the risks associated with directly investing in the securities of foreign issuers.

Derivatives. A derivative is a financial instrument that has a value based on—or “derived from”—the values of other assets, reference rates, or indexes. Derivatives may relate to a wide variety of underlying references, such as commodities, stocks, bonds, interest rates, currency exchange rates, and related indexes. Derivatives include futures contracts and options on futures contracts, certain forward-commitment transactions, options on securities, caps, floors, collars, swap agreements, and certain other financial instruments. Some derivatives, such as futures contracts and certain options, are traded on U.S. commodity and securities exchanges, while other derivatives, such as swap agreements, may be privately negotiated and entered into in the over-the-counter market (OTC Derivatives) or may be cleared through a clearinghouse (Cleared Derivatives) and traded on an exchange or swap execution facility. As a result of the Dodd-Frank Wall Street Reform and Consumer Protection Act (the Dodd-Frank Act), certain swap agreements, such as certain standardized credit default and interest rate swap agreements, must be cleared through a clearinghouse and traded on an exchange or swap execution facility. This could result in an increase in the overall costs of such transactions. While the intent of derivatives regulatory reform is to mitigate risks associated with derivatives markets, the new regulations could, among other things, increase liquidity and decrease pricing for more standardized products while decreasing liquidity and increasing pricing for less standardized products. The risks associated with the use of derivatives are different from, and possibly greater than, the risks associated with investing directly in the securities or assets on which the derivatives are based.

Derivatives may be used for a variety of purposes, including—but not limited to—hedging, managing risk, seeking to stay fully invested, seeking to reduce transaction costs, seeking to simulate an investment in equity or debt securities or other investments, and seeking to add value by using derivatives to more efficiently implement portfolio positions when derivatives are favorably priced relative to equity or debt securities or other investments. Some investors may use derivatives primarily for speculative purposes while other uses of derivatives may not constitute speculation. There is no assurance that any derivatives strategy used by a fund’s advisor will succeed. The other parties to the funds’ OTC Derivatives contracts (usually referred to as “counterparties”) will not be considered the issuers thereof for purposes of certain provisions of the 1940 Act and the IRC, although such OTC Derivatives may qualify as securities or investments under such laws. The funds’ advisors, however, will monitor and adjust, as appropriate, the funds’ credit risk exposure to OTC Derivative counterparties.

Derivative products are highly specialized instruments that require investment techniques and risk analyses different from those associated with stocks, bonds, and other traditional investments. The use of a derivative requires an understanding not only of the underlying instrument but also of the derivative itself, without the benefit of observing the performance of the derivative under all possible market conditions.

When the fund enters into a Cleared Derivative, an initial margin deposit with a Futures Commission Merchant (FCM) is required. Initial margin deposits are typically calculated as an amount equal to the volatility in market value of a Cleared Derivative over a fixed period. If the value of the fund’s Cleared Derivatives declines, the fund will be required to make additional “variation margin” payments to the FCM to settle the change in value. If the value of the fund’s Cleared Derivatives increases, the FCM will be required to make additional “variation margin” payments to the fund to settle the change in value. This process is known as “marking-to-market” and is calculated on a daily basis.

For OTC Derivatives, the fund is subject to the risk that a loss may be sustained as a result of the insolvency or bankruptcy of the counterparty or the failure of the counterparty to make required payments or otherwise comply with the terms of the contract. Additionally, the use of credit derivatives can result in losses if a fund’s advisor does not correctly evaluate the creditworthiness of the issuer on which the credit derivative is based.

Derivatives may be subject to liquidity risk, which exists when a particular derivative is difficult to purchase or sell. If a derivative transaction is particularly large or if the relevant market is illiquid (as is the case with certain OTC Derivatives), it may not be possible to initiate a transaction or liquidate a position at an advantageous time or price.

Derivatives may be subject to pricing or “basis” risk, which exists when a particular derivative becomes extraordinarily expensive relative to historical prices or the prices of corresponding cash market instruments. Under certain market conditions, it may not be economically feasible to initiate a transaction or liquidate a position in time to avoid a loss or take advantage of an opportunity.

Because certain derivatives have a leverage component, adverse changes in the value or level of the underlying asset, reference rate, or index can result in a loss substantially greater than the amount invested in the derivative itself. Certain

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derivatives have the potential for unlimited loss, regardless of the size of the initial investment. A derivative transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

Like most other investments, derivative instruments are subject to the risk that the market value of the instrument will change in a way detrimental to a fund’s interest. A fund bears the risk that its advisor will incorrectly forecast future market trends or the values of assets, reference rates, indexes, or other financial or economic factors in establishing derivative positions for the fund. If the advisor attempts to use a derivative as a hedge against, or as a substitute for, a portfolio investment, the fund will be exposed to the risk that the derivative will have or will develop imperfect or no correlation with the portfolio investment. This could cause substantial losses for the fund. Although hedging strategies involving derivative instruments can reduce the risk of loss, they can also reduce the opportunity for gain or even result in losses by offsetting favorable price movements in other fund investments. Many derivatives (in particular, OTC Derivatives) are complex and often valued subjectively. Improper valuations can result in increased cash payment requirements to counterparties or a loss of value to a fund.

Exchange-Traded Funds. A fund may purchase shares of exchange-traded funds (ETFs). Typically, a fund would purchase ETF shares for the same reason it would purchase (and as an alternative to purchasing) futures contracts: to obtain exposure to all or a portion of the stock or bond market. ETF shares enjoy several advantages over futures. Depending on the market, the holding period, and other factors, ETF shares can be less costly and more tax-efficient than futures. In addition, ETF shares can be purchased for smaller sums, offer exposure to market sectors and styles for which there is no suitable or liquid futures contract, and do not involve leverage.

An investment in an ETF generally presents the same principal risks as an investment in a conventional fund (i.e., one that is not exchange-traded) that has the same investment objective, strategies, and policies. The price of an ETF can fluctuate within a wide range, and a fund could lose money investing in an ETF if the prices of the securities owned by the ETF go down. In addition, ETFs are subject to the following risks that do not apply to conventional funds: (1) the market price of an ETF’s shares may trade at a discount or a premium to their net asset value; (2) an active trading market for an ETF’s shares may not develop or be maintained; and (3) trading of an ETF’s shares may be halted by the activation of individual or marketwide trading halts (which halt trading for a specific period of time when the price of a particular security or overall market prices decline by a specified percentage). Trading of an ETF’s shares may also be halted if the shares are delisted from the exchange without first being listed on another exchange or if the listing exchange’s officials determine that such action is appropriate in the interest of a fair and orderly market or for the protection of investors.

Most ETFs are investment companies. Therefore, a fund’s purchases of ETF shares generally are subject to the limitations on, and the risks of, a fund’s investments in other investment companies, which are described under the heading “Other Investment Companies.”

Vanguard ETF^®* Shares are exchange-traded shares that represent an interest in an investment portfolio held by Vanguard funds. A fund’s investments in Vanguard ETF Shares are also generally subject to the descriptions, limitations, and risks described under the heading “Other Investment Companies,” except as provided by an exemption granted by the SEC that permits registered investment companies to invest in a Vanguard fund that issues ETF Shares beyond the limits of Section 12(d)(1) of the 1940 Act, subject to certain terms and conditions.

* U.S. Patent Nos. 6,879,964; 7,337,138; 7,720,749; 7,925,573; 8,090,646; and 8,417,623.

Foreign Securities. Typically, foreign securities are considered to be equity or debt securities issued by entities organized, domiciled, or with a principal executive office outside the United States, such as foreign corporations and governments. Securities issued by certain companies organized outside the United States may not be deemed to be foreign securities if the company’s principal operations are conducted from the United States or when the company’s equity securities trade principally on a U.S. stock exchange. Foreign securities may trade in U.S. or foreign securities markets. A fund may make foreign investments either directly by purchasing foreign securities or indirectly by purchasing depositary receipts or depositary shares of similar instruments (depositary receipts) for foreign securities. Direct investments in foreign securities may be made either on foreign securities exchanges or in the over-the-counter (OTC) markets. Investing in foreign securities involves certain special risk considerations that are not typically associated with investing in securities of U.S. companies or governments.

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Because foreign issuers are not generally subject to uniform accounting, auditing, and financial reporting standards and practices comparable to those applicable to U.S. issuers, there may be less publicly available information about certain foreign issuers than about U.S. issuers. Evidence of securities ownership may be uncertain in many foreign countries. As a result, there are multiple risks that could result in a loss to the fund, including, but not limited to, the risk that a fund’s trade details could be incorrectly or fraudulently entered at the time of a transaction. Securities of foreign issuers are generally more volatile and less liquid than securities of comparable U.S. issuers, and foreign investments may be effected through structures that may be complex or confusing. In certain countries, there is less government supervision and regulation of stock exchanges, brokers, and listed companies than in the United States. The risk that securities traded on foreign exchanges may be suspended, either by the issuers themselves, by an exchange, or by government authorities, is also heightened. In addition, with respect to certain foreign countries, there is the possibility of expropriation or confiscatory taxation, political or social instability, war, terrorism, nationalization, limitations on the removal of funds or other assets, or diplomatic developments that could affect U.S. investments in those countries. Additionally, economic or other sanctions imposed on the United States by a foreign country, or imposed on a foreign country or issuer by the United States, could impair a fund’s ability to buy, sell, hold, receive, deliver, or otherwise transact in certain investment securities. Sanctions could also affect the value and/or liquidity of a foreign security.

Although an advisor will endeavor to achieve the most favorable execution costs for a fund’s portfolio transactions in foreign securities under the circumstances, commissions and other transaction costs are generally higher than those on U.S. securities. In addition, it is expected that the custodian arrangement expenses for a fund that invests primarily in foreign securities will be somewhat greater than the expenses for a fund that invests primarily in domestic securities. Additionally, bankruptcy laws vary by jurisdiction and cash deposits may be subject to a custodian’s creditors. Certain foreign governments levy withholding or other taxes against dividend and interest income from, capital gains on the sale of, or transactions in foreign securities. Although in some countries a portion of these taxes is recoverable by the fund, the nonrecovered portion of foreign withholding taxes will reduce the income received from such securities.

The value of the foreign securities held by a fund that are not U.S. dollar-denominated may be significantly affected by changes in currency exchange rates. The U.S. dollar value of a foreign security generally decreases when the value of the U.S. dollar rises against the foreign currency in which the security is denominated, and it tends to increase when the value of the U.S. dollar falls against such currency (as discussed under the heading “Foreign Securities—Foreign Currency Transactions,” a fund may attempt to hedge its currency risks). In addition, the value of fund assets may be affected by losses and other expenses incurred from converting between various currencies in order to purchase and sell foreign securities, as well as by currency restrictions, exchange control regulations, currency devaluations, and political and economic developments.

Foreign Securities—Foreign Currency Transactions. The value in U.S. dollars of a fund’s non-dollar-denominated foreign securities may be affected favorably or unfavorably by changes in foreign currency exchange rates and exchange control regulations, and the fund may incur costs in connection with conversions between various currencies. To seek to minimize the impact of such factors on net asset values, a fund may engage in foreign currency transactions in connection with its investments in foreign securities. A fund will enter into foreign currency transactions only to attempt to “hedge” the currency risk associated with investing in foreign securities. Although such transactions tend to minimize the risk of loss that would result from a decline in the value of the hedged currency, they also may limit any potential gain that might result should the value of such currency increase.

Currency exchange transactions may be conducted either on a spot (i.e., cash) basis at the rate prevailing in the currency exchange market or through forward contracts to purchase or sell foreign currencies. A forward currency contract involves an obligation to purchase or sell a specific currency at a future date, which may be any fixed number of days from the date of the contract agreed upon by the parties, at a price set at the time of the contract. These contracts are entered into with large commercial banks or other currency traders who are participants in the interbank market. Currency exchange transactions also may be effected through the use of swap agreements or other derivatives.

Currency exchange transactions may be considered borrowings. A currency exchange transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

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By entering into a forward contract for the purchase or sale of foreign currency involved in underlying security transactions, a fund may be able to protect itself against part or all of the possible loss between trade and settlement dates for that purchase or sale resulting from an adverse change in the relationship between the U.S. dollar and such foreign currency. This practice is sometimes referred to as “transaction hedging.” In addition, when the advisor reasonably believes that a particular foreign currency may suffer a substantial decline against the U.S. dollar, a fund may enter into a forward contract to sell an amount of foreign currency approximating the value of some or all of its portfolio securities denominated in such foreign currency. This practice is sometimes referred to as “portfolio hedging.” Similarly, when the advisor reasonably believes that the U.S. dollar may suffer a substantial decline against a foreign currency, a fund may enter into a forward contract to buy that foreign currency for a fixed dollar amount.

A fund may also attempt to hedge its foreign currency exchange rate risk by engaging in currency futures, options, and “cross-hedge” transactions. In cross-hedge transactions, a fund holding securities denominated in one foreign currency will enter into a forward currency contract to buy or sell a different foreign currency (one that the advisor reasonably believes generally tracks the currency being hedged with regard to price movements). The advisor may select the tracking (or substitute) currency rather than the currency in which the security is denominated for various reasons, including in order to take advantage of pricing or other opportunities presented by the tracking currency or to take advantage of a more liquid or more efficient market for the tracking currency. Such cross-hedges are expected to help protect a fund against an increase or decrease in the value of the U.S. dollar against certain foreign currencies.

A fund may hold a portion of its assets in bank deposits denominated in foreign currencies so as to facilitate investment in foreign securities as well as protect against currency fluctuations and the need to convert such assets into U.S. dollars (thereby also reducing transaction costs). To the extent these assets are converted back into U.S. dollars, the value of the assets so maintained will be affected favorably or unfavorably by changes in foreign currency exchange rates and exchange control regulations.

The forecasting of currency market movement is extremely difficult, and whether any hedging strategy will be successful is highly uncertain. Moreover, it is impossible to forecast with precision the market value of portfolio securities at the expiration of a forward currency contract. Accordingly, a fund may be required to buy or sell additional currency on the spot market (and bear the expense of such transaction) if its advisor’s predictions regarding the movement of foreign currency or securities markets prove inaccurate. In addition, the use of cross-hedging transactions may involve special risks and may leave a fund in a less advantageous position than if such a hedge had not been established. Because forward currency contracts are privately negotiated transactions, there can be no assurance that a fund will have flexibility to roll over a forward currency contract upon its expiration if it desires to do so. Additionally, there can be no assurance that the other party to the contract will perform its services thereunder.

Foreign Securities—Foreign Investment Companies. Some of the countries in which a fund may invest may not permit, or may place economic restrictions on, direct investment by outside investors. Fund investments in such countries may be permitted only through foreign government-approved or authorized investment vehicles, which may include other investment companies. Such investments may be made through registered or unregistered closed-end investment companies that invest in foreign securities. Investing through such vehicles may involve layered fees or expenses and may also be subject to the limitations on, and the risks of, a fund’s investments in other investment companies, which are described under the heading “Other Investment Companies.”

Futures Contracts and Options on Futures Contracts. Futures contracts and options on futures contracts are derivatives. A futures contract is a standardized agreement between two parties to buy or sell at a specific time in the future a specific quantity of a commodity at a specific price. The commodity may consist of an asset, a reference rate, or an index. A security futures contract relates to the sale of a specific quantity of shares of a single equity security or a narrow-based securities index. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying commodity. The buyer of a futures contract enters into an agreement to purchase the underlying commodity on the settlement date and is said to be “long” the contract. The seller of a futures contract enters into an agreement to sell the underlying commodity on the settlement date and is said to be “short” the contract. The price at which a futures contract is entered into is established either in the electronic marketplace or by open outcry on the floor of an exchange between exchange members acting as traders or brokers. Open futures contracts can be liquidated or closed out by physical delivery of the underlying commodity or payment of the cash settlement amount on the settlement date, depending on the terms of the particular contract. Some financial futures contracts (such as security futures) provide for physical settlement at maturity. Other financial futures contracts (such as those relating to interest rates, foreign currencies, and broad-based

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securities indexes) generally provide for cash settlement at maturity. In the case of cash-settled futures contracts, the cash settlement amount is equal to the difference between the final settlement or market price for the relevant commodity on the last trading day of the contract and the price for the relevant commodity agreed upon at the outset of the contract. Most futures contracts, however, are not held until maturity but instead are “offset” before the settlement date through the establishment of an opposite and equal futures position.

The purchaser or seller of a futures contract is not required to deliver or pay for the underlying commodity unless the contract is held until the settlement date. However, both the purchaser and seller are required to deposit “initial margin” with a futures commission merchant (FCM) when the futures contract is entered into. Initial margin deposits are typically calculated as an amount equal to the volatility in market value of a contract over a fixed period. If the value of the fund’s position declines, the fund will be required to make additional “variation margin” payments to the FCM to settle the change in value. If the value of the fund’s position increases, the FCM will be required to make additional “variation margin” payments to the fund to settle the change in value. This process is known as “marking-to-market” and is calculated on a daily basis. A futures transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

An option on a futures contract (or futures option) conveys the right, but not the obligation, to purchase (in the case of a call option) or sell (in the case of a put option) a specific futures contract at a specific price (called the “exercise” or “strike” price) any time before the option expires. The seller of an option is called an option writer. The purchase price of an option is called the premium. The potential loss to an option buyer is limited to the amount of the premium plus transaction costs. This will be the case, for example, if the option is held and not exercised prior to its expiration date. Generally, an option writer sells options with the goal of obtaining the premium paid by the option buyer. If an option sold by an option writer expires without being exercised, the writer retains the full amount of the premium. The option writer, however, has unlimited economic risk because its potential loss, except to the extent offset by the premium received when the option was written, is equal to the amount the option is “in-the-money” at the expiration date. A call option is in-the-money if the value of the underlying futures contract exceeds the exercise price of the option. A put option is in-the-money if the exercise price of the option exceeds the value of the underlying futures contract. Generally, any profit realized by an option buyer represents a loss for the option writer.

A fund that takes the position of a writer of a futures option is required to deposit and maintain initial and variation margin with respect to the option, as previously described in the case of futures contracts. A futures option transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

Each Fund intends to comply with Rule 4.5 under the Commodity Exchange Act (CEA), under which a mutual fund may be excluded from the definition of the term Commodity Pool Operator (CPO) if the fund meets certain conditions such as limiting its investments in certain CEA-regulated instruments (e.g., futures, options, or swaps) and complying with certain marketing restrictions. Accordingly, Vanguard is not subject to registration or regulation as a CPO with respect to each Fund under the CEA. Each Fund will only enter into futures contracts and futures options that are traded on a U.S. or foreign exchange, board of trade, or similar entity or that are quoted on an automated quotation system.

Futures Contracts and Options on Futures Contracts—Risks. The risk of loss in trading futures contracts and in writing futures options can be substantial because of the low margin deposits required, the extremely high degree of leverage involved in futures and options pricing, and the potential high volatility of the futures markets. As a result, a relatively small price movement in a futures position may result in immediate and substantial loss (or gain) for the investor. For example, if at the time of purchase, 10% of the value of the futures contract is deposited as margin, a subsequent 10% decrease in the value of the futures contract would result in a total loss of the margin deposit, before any deduction for the transaction costs, if the account were then closed out. A 15% decrease would result in a loss equal to 150% of the original margin deposit if the contract were closed out. Thus, a purchase or sale of a futures contract, and the writing of a futures option, may result in losses in excess of the amount invested in the position. In the event of adverse price movements, a fund would continue to be required to make daily cash payments to maintain its required margin. In such situations, if the fund has insufficient cash, it may have to sell portfolio securities to meet daily margin requirements (and segregation requirements, if applicable) at a time when it may be disadvantageous to do so. In

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addition, on the settlement date, a fund may be required to make delivery of the instruments underlying the futures positions it holds.

A fund could suffer losses if it is unable to close out a futures contract or a futures option because of an illiquid secondary market. Futures contracts and futures options may be closed out only on an exchange that provides a secondary market for such products. However, there can be no assurance that a liquid secondary market will exist for any particular futures product at any specific time. Thus, it may not be possible to close a futures or option position. Moreover, most futures exchanges limit the amount of fluctuation permitted in futures contract prices during a single trading day. The daily limit establishes the maximum amount that the price of a futures contract may vary either up or down from the previous day’s settlement price at the end of a trading session. Once the daily limit has been reached in a particular type of contract, no trades may be made on that day at a price beyond that limit. The daily limit governs only price movement during a particular trading day, and therefore does not limit potential losses because the limit may prevent the liquidation of unfavorable positions. Futures contract prices have occasionally moved to the daily limit for several consecutive trading days with little or no trading, thereby preventing prompt liquidation of future positions and subjecting some futures traders to substantial losses. The inability to close futures and options positions also could have an adverse impact on the ability to hedge a portfolio investment or to establish a substitute for a portfolio investment.

U.S. Treasury futures are generally not subject to such daily limits.

A fund bears the risk that its advisor will incorrectly predict future market trends. If the advisor attempts to use a futures

contract or a futures option as a hedge against, or as a substitute for, a portfolio investment, the fund will be exposed to the risk that the futures position will have or will develop imperfect or no correlation with the portfolio investment. This could cause substantial losses for the fund. Although hedging strategies involving futures products can reduce the risk of loss, they can also reduce the opportunity for gain or even result in losses by offsetting favorable price movements in other fund investments.

A fund could lose margin payments it has deposited with its FCM if, for example, the FCM breaches its agreement with the fund or becomes insolvent or goes into bankruptcy. In that event, the fund may be entitled to return of margin owed to it only in proportion to the amount received by the FCM’s other customers, potentially resulting in losses to the fund.

Interfund Borrowing and Lending. The SEC has granted an exemption permitting registered open-end Vanguard funds to participate in Vanguard’s interfund lending program. This program allows the Vanguard funds to borrow money from and lend money to each other for temporary or emergency purposes. The program is subject to a number of conditions, including, among other things, the requirements that (1) no fund may borrow or lend money through the program unless it receives a more favorable interest rate than is typically available from a bank for a comparable transaction, (2) no fund may lend money if the loan would cause its aggregate outstanding loans through the program to exceed 15% of its net assets at the time of the loan, and (3) a fund’s interfund loans to any one fund shall not exceed 5% of the lending fund’s net assets. In addition, a Vanguard fund may participate in the program only if and to the extent that such participation is consistent with the fund’s investment objective and investment policies. The boards of trustees of the Vanguard funds are responsible for overseeing the interfund lending program. Any delay in repayment to a lending fund could result in a lost investment opportunity or additional borrowing costs.

Investing for Control. Each Vanguard fund invests in securities and other instruments for the sole purpose of achieving a specific investment objective. As such, a Vanguard fund does not seek to acquire, individually or collectively with any other Vanguard fund, enough of a company’s outstanding voting stock to have control over management decisions. A Vanguard fund does not invest for the purpose of controlling a company’s management.

Options. An option is a derivative. An option on a security (or index) is a contract that gives the holder of the option, in return for the payment of a “premium,” the right, but not the obligation, to buy from (in the case of a call option) or sell to (in the case of a put option) the writer of the option the security underlying the option (or the cash value of the index) at a specified exercise price prior to the expiration date of the option. The writer of an option on a security has the obligation upon exercise of the option to deliver the underlying security upon payment of the exercise price (in the case of a call option) or to pay the exercise price upon delivery of the underlying security (in the case of a put option). The writer of an option on an index has the obligation upon exercise of the option to pay an amount equal to the cash value of the index minus the exercise price, multiplied by the specified multiplier for the index option. The multiplier for an index option determines the size of the investment position the option represents. Unlike exchange-traded options, which are standardized with respect to the underlying instrument, expiration date, contract size, and strike price, the

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terms of over-the-counter (OTC) options (options not traded on exchanges) generally are established through negotiation with the other party to the option contract. Although this type of arrangement allows the purchaser or writer greater flexibility to tailor an option to its needs, OTC options generally involve credit risk to the counterparty whereas for exchange-traded, centrally cleared options, credit risk is mutualized through the involvement of the applicable clearing house.

The buyer (or holder) of an option is said to be “long” the option, while the seller (or writer) of an option is said to be “short” the option. A call option grants to the holder the right to buy (and obligates the writer to sell) the underlying security at the strike price, which is the predetermined price at which the option may be exercised. A put option grants to the holder the right to sell (and obligates the writer to buy) the underlying security at the strike price. The purchase price of an option is called the “premium.” The potential loss to an option buyer is limited to the amount of the premium plus transaction costs. This will be the case if the option is held and not exercised prior to its expiration date. Generally, an option writer sells options with the goal of obtaining the premium paid by the option buyer, but that person could also seek to profit from an anticipated rise or decline in option prices. If an option sold by an option writer expires without being exercised, the writer retains the full amount of the premium. The option writer, however, has unlimited economic risk because its potential loss, except to the extent offset by the premium received when the option was written, is equal to the amount the option is “in-the-money” at the expiration date. A call option is in-the-money if the value of the underlying position exceeds the exercise price of the option. A put option is in-the-money if the exercise price of the option exceeds the value of the underlying position. Generally, any profit realized by an option buyer represents a loss for the option writer. The writing of an option will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

If a trading market, in particular options, were to become unavailable, investors in those options (such as the funds) would be unable to close out their positions until trading resumes, and they may be faced with substantial losses if the value of the underlying instrument moves adversely during that time. Even if the market were to remain available, there may be times when options prices will not maintain their customary or anticipated relationships to the prices of the underlying instruments and related instruments. Lack of investor interest, changes in volatility, or other factors or conditions might adversely affect the liquidity, efficiency, continuity, or even the orderliness of the market for particular options.

A fund bears the risk that its advisor will not accurately predict future market trends. If the advisor attempts to use an option as a hedge against, or as a substitute for, a portfolio investment, the fund will be exposed to the risk that the option will have or will develop imperfect or no correlation with the portfolio investment, which could cause substantial losses for the fund. Although hedging strategies involving options can reduce the risk of loss, they can also reduce the opportunity for gain or even result in losses by offsetting favorable price movements in other fund investments. Many options, in particular OTC options, are complex and often valued based on subjective factors. Improper valuations can result in increased cash payment requirements to counterparties or a loss of value to a fund.

OTC Swap Agreements. An over-the-counter (OTC) swap agreement, which is a type of derivative, is an agreement between two parties (counterparties) to exchange payments at specified dates (periodic payment dates) on the basis of a specified amount (notional amount) with the payments calculated with reference to a specified asset, reference rate, or index.

Examples of OTC swap agreements include, but are not limited to, interest rate swaps, credit default swaps, equity swaps, commodity swaps, foreign currency swaps, index swaps, excess return swaps, and total return swaps. Most OTC swap agreements provide that when the periodic payment dates for both parties are the same, payments are netted and only the net amount is paid to the counterparty entitled to receive the net payment. Consequently, a fund’s current obligations (or rights) under an OTC swap agreement will generally be equal only to the net amount to be paid or received under the agreement, based on the relative values of the positions held by each counterparty. OTC swap agreements allow for a wide variety of transactions. For example, fixed rate payments may be exchanged for floating rate payments; U.S. dollar-denominated payments may be exchanged for payments denominated in a different currency; and payments tied to the price of one asset, reference rate, or index may be exchanged for payments tied to the price of another asset, reference rate, or index.

An OTC option on an OTC swap agreement, also called a “swaption,” is an option that gives the buyer the right, but not the obligation, to enter into a swap on a future date in exchange for paying a market-based “premium.” A receiver

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swaption gives the owner the right to receive the total return of a specified asset, reference rate, or index. A payer swaption gives the owner the right to pay the total return of a specified asset, reference rate, or index. Swaptions also include options that allow an existing swap to be terminated or extended by one of the counterparties.

The use of OTC swap agreements by a fund entails certain risks, which may be different from, or possibly greater than, the risks associated with investing directly in the securities and other investments that are the referenced asset for the swap agreement. OTC swaps are highly specialized instruments that require investment techniques, risk analyses, and tax planning different from those associated with stocks, bonds, and other traditional investments. The use of an OTC swap requires an understanding not only of the referenced asset, reference rate, or index but also of the swap itself, without the benefit of observing the performance of the swap under all possible market conditions.

OTC swap agreements may be subject to liquidity risk, which exists when a particular swap is difficult to purchase or sell. If an OTC swap transaction is particularly large or if the relevant market is illiquid (as is the case with many OTC swaps), it may not be possible to initiate a transaction or liquidate a position at an advantageous time or price, which may result in significant losses. In addition, OTC swap transactions may be subject to a fund’s limitation on investments in illiquid securities.

OTC swap agreements may be subject to pricing risk, which exists when a particular swap becomes extraordinarily expensive or inexpensive relative to historical prices or the prices of corresponding cash market instruments. Under certain market conditions, it may not be economically feasible to initiate a transaction or liquidate a position in time to avoid a loss or take advantage of an opportunity or to realize the intrinsic value of the OTC swap agreement.

Because certain OTC swap agreements have a leverage component, adverse changes in the value or level of the underlying asset, reference rate, or index can result in a loss substantially greater than the amount invested in the swap itself. Certain OTC swaps have the potential for unlimited loss, regardless of the size of the initial investment. A leveraged OTC swap transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

Like most other investments, OTC swap agreements are subject to the risk that the market value of the instrument will change in a way detrimental to a fund’s interest. A fund bears the risk that its advisor will not accurately forecast future market trends or the values of assets, reference rates, indexes, or other economic factors in establishing OTC swap positions for the fund. If the advisor attempts to use an OTC swap as a hedge against, or as a substitute for, a portfolio investment, the fund will be exposed to the risk that the OTC swap will have or will develop imperfect or no correlation with the portfolio investment. This could cause substantial losses for the fund. Although hedging strategies involving OTC swap instruments can reduce the risk of loss, they can also reduce the opportunity for gain or even result in losses by offsetting favorable price movements in other fund investments. Many OTC swaps are complex and often valued subjectively. Improper valuations can result in increased cash payment requirements to counterparties or a loss of value to a fund.

The use of an OTC swap agreement also involves the risk that a loss may be sustained as a result of the insolvency or bankruptcy of the counterparty or the failure of the counterparty to make required payments or otherwise comply with the terms of the agreement. Additionally, the use of credit default swaps can result in losses if a fund’s advisor does not correctly evaluate the creditworthiness of the issuer on which the credit swap is based.

The market for OTC swaps and swaptions is a relatively new market. It is possible that developments in the market could adversely affect a fund, including its ability to terminate existing OTC swap agreements or to realize amounts to be received under such agreements. As previously noted under the heading “Derivatives,” under the Dodd-Frank Act, certain swaps that may be used by a fund may be cleared through a clearinghouse and traded on an exchange or swap execution facility.

Other Investment Companies. A fund may invest in other investment companies to the extent permitted by applicable law or SEC exemption. Under Section 12(d)(1) of the 1940 Act, a fund generally may invest up to 10% of its assets in shares of investment companies and up to 5% of its assets in any one investment company, as long as no investment represents more than 3% of the voting stock of an acquired investment company. In addition, no funds for which Vanguard acts as an advisor may, in the aggregate, own more than 10% of the voting stock of a closed-end investment company. The 1940 Act and related rules provide certain exemptions from these restrictions, for example, for funds that invest in other funds within the same group of investment companies. If a fund invests in other investment companies,

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shareholders will bear not only their proportionate share of the fund’s expenses (including operating expenses and the fees of the advisor), but they also may indirectly bear similar expenses of the underlying investment companies. Certain investment companies, such as business development companies (BDCs), are more akin to operating companies and, as such, their expenses are not direct expenses paid by fund shareholders and are not used to calculate the fund’s net asset value. SEC rules nevertheless require that any expenses incurred by a BDC be included in a fund’s expense ratio as “Acquired Fund Fees and Expenses.” The expense ratio of a fund that holds a BDC will thus overstate what the fund actually spends on portfolio management, administrative services, and other shareholder services by an amount equal to these Acquired Fund Fees and Expenses. The Acquired Fund Fees and Expenses are not included in a fund’s financial statements, which provide a clearer picture of a fund’s actual operating expenses. Shareholders would also be exposed to the risks associated not only with the investments of the fund but also with the portfolio investments of the underlying investment companies. Certain types of investment companies, such as closed-end investment companies, issue a fixed number of shares that typically trade on a stock exchange or over-the-counter at a premium or discount to their net asset value. Others are continuously offered at net asset value but also may be traded on the secondary market.

Preferred Stock. Preferred stock represents an equity or ownership interest in an issuer. Preferred stock normally pays dividends at a specified rate and has precedence over common stock in the event the issuer is liquidated or declares bankruptcy. However, in the event an issuer is liquidated or declares bankruptcy, the claims of owners of bonds take precedence over the claims of those who own preferred and common stock. Preferred stock, unlike common stock, often has a stated dividend rate payable from the corporation’s earnings. Preferred stock dividends may be cumulative or noncumulative, participating, or auction rate. “Cumulative” dividend provisions require all or a portion of prior unpaid dividends to be paid before dividends can be paid to the issuer’s common stock. “Participating” preferred stock may be entitled to a dividend exceeding the stated dividend in certain cases. If interest rates rise, the fixed dividend on preferred stocks may be less attractive, causing the price of such stocks to decline. Preferred stock may have mandatory sinking fund provisions, as well as provisions allowing the stock to be called or redeemed, which can limit the benefit of a decline in interest rates. Preferred stock is subject to many of the risks to which common stock and debt securities are subject. In addition, preferred stock may be subject to more abrupt or erratic price movements than common stock or debt securities because preferred stock may trade with less frequency and in more limited volume.

Real Estate Investment Trusts (REITs). An equity REIT owns real estate properties directly and generates income from rental and lease payments. Equity REITs also have the potential to generate capital gains as properties are sold at a profit. A mortgage REIT makes construction, development, and long-term mortgage loans to commercial real estate developers and earns interest income on these loans. A hybrid REIT holds both properties and mortgages. To avoid taxation at the corporate level, REITs must distribute most of their earnings to shareholders.

Investments in REITs are subject to many of the same risks as direct investments in real estate. In general, real estate values can be affected by a variety of factors, including, but not limited to, supply and demand for properties, general or local economic conditions, and the strength of specific industries that rent properties. Ultimately, a REIT’s performance depends on the types and locations of the properties it owns and on how well the REIT manages its properties. For example, rental income could decline because of extended vacancies, increased competition from nearby properties, tenants’ failure to pay rent, regulatory limitations on rents, fluctuations in rental income, variations in market rental rates, or incompetent management. Property values could decrease because of overbuilding in the area, environmental liabilities, uninsured damages caused by natural disasters, a general decline in the neighborhood, losses because of casualty or condemnation, increases in property taxes, or changes in zoning laws.

The value of a REIT may also be affected by changes in interest rates. Rising interest rates generally increase the cost of financing for real estate projects, which could cause the value of an equity REIT to decline. During periods of declining interest rates, mortgagors may elect to prepay mortgages held by mortgage REITs, which could lower or diminish the yield on the REIT. REITs are also subject to heavy cash-flow dependency, default by borrowers, and changes in tax and regulatory requirements. In addition, a REIT may fail to meet the requirements for qualification and taxation as a REIT under the IRC and/or fail to maintain exemption from the 1940 Act.

Repurchase Agreements. A repurchase agreement is an agreement under which a fund acquires a debt security (generally a security issued by the U.S. government or an agency thereof, a banker’s acceptance, or a certificate of deposit) from a bank, a broker, or a dealer and simultaneously agrees to resell such security to the seller at an agreed-upon price and date (normally, the next business day). Because the security purchased constitutes collateral for the repurchase obligation, a repurchase agreement may be considered a loan that is collateralized by the security purchased.

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The resale price reflects an agreed-upon interest rate effective for the period the instrument is held by a fund and is unrelated to the interest rate on the underlying instrument. In these transactions, the securities acquired by a fund (including accrued interest earned thereon) must have a total value in excess of the value of the repurchase agreement and be held by a custodian bank until repurchased. In addition, the investment advisor will monitor a fund’s repurchase agreement transactions generally and will evaluate the creditworthiness of any bank, broker, or dealer party to a repurchase agreement relating to a fund. The aggregate amount of any such agreements is not limited, except to the extent required by law.

The use of repurchase agreements involves certain risks. One risk is the seller’s ability to pay the agreed-upon repurchase price on the repurchase date. If the seller defaults, the fund may incur costs in disposing of the collateral, which would reduce the amount realized thereon. If the seller seeks relief under bankruptcy laws, the disposition of the collateral may be delayed or limited. For example, if the other party to the agreement becomes insolvent and subject to liquidation or reorganization under bankruptcy or other laws, a court may determine that the underlying security is collateral for a loan by the fund not within its control, and therefore the realization by the fund on such collateral may be automatically stayed. Finally, it is possible that the fund may not be able to substantiate its interest in the underlying security and may be deemed an unsecured creditor of the other party to the agreement.

Restricted and Illiquid Securities. Illiquid securities are securities that cannot be sold or disposed of within seven days in the ordinary course of business at approximately the price at which they are valued. The SEC generally limits aggregate holdings of illiquid securities by a mutual fund to 15% of its net assets (5% for money market funds). A fund may experience difficulty valuing and selling illiquid securities and, in some cases, may be unable to value or sell certain illiquid securities for an indefinite period of time. Illiquid securities may include a wide variety of investments, such as (1) repurchase agreements maturing in more than seven days (unless the agreements have demand/redemption features), (2) OTC options contracts and certain other derivatives (including certain swap agreements), (3) fixed time deposits that are not subject to prepayment or do not provide for withdrawal penalties upon prepayment (other than overnight deposits), (4) certain loan interests and other direct debt instruments, (5) certain municipal lease obligations, (6) private equity investments, (7) commercial paper issued pursuant to Section 4(a)(2) of the 1933 Act, and (8) securities whose disposition is restricted under the federal securities laws. Illiquid securities include restricted, privately placed securities that, under the federal securities laws, generally may be resold only to qualified institutional buyers. If a substantial market develops for a restricted security held by a fund, it may be treated as a liquid security in accordance with procedures and guidelines approved by the board of trustees. This generally includes securities that are unregistered, that can be sold to qualified institutional buyers in accordance with Rule 144A under the 1933 Act, or that are exempt from registration under the 1933 Act, such as commercial paper. Although a fund’s advisor monitors the liquidity of restricted securities, the board of trustees oversees and retains ultimate responsibility for the advisor’s liquidity determinations. Several factors that the trustees consider in monitoring these decisions include the valuation of a security; the availability of qualified institutional buyers, brokers, and dealers that trade in the security; and the availability of information about the security’s issuer.

Reverse Repurchase Agreements. In a reverse repurchase agreement, a fund sells a security to another party, such as a bank or broker-dealer, in return for cash and agrees to repurchase that security at an agreed-upon price and time. Under a reverse repurchase agreement, the fund continues to receive any principal and interest payments on the underlying security during the term of the agreement. Reverse repurchase agreements involve the risk that the market value of securities retained by the fund may decline below the repurchase price of the securities sold by the fund that it is obligated to repurchase. In addition to the risk of such a loss, fees charged to the fund may exceed the return the fund earns from investing the proceeds received from the reverse repurchase agreement transaction. A reverse repurchase agreement may be considered a borrowing transaction for purposes of the 1940 Act. A reverse repurchase agreement transaction will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by a fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.” A fund will enter into reverse repurchase agreements only with parties whose creditworthiness has been reviewed and found satisfactory by the advisor. If the buyer in a reverse repurchase agreement becomes insolvent or files for bankruptcy, a fund’s use of proceeds from the sale may be restricted while the other party or its trustee or receiver determines if it will honor the fund’s right to repurchase the securities. If the fund is unable to recover the securities it sold in a reverse repurchase agreement, it would realize a loss equal to the difference between the value of the securities and the payment it received for them.

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Securities Lending. A fund may lend its investment securities to qualified institutional investors (typically brokers, dealers, banks, or other financial institutions) who may need to borrow securities in order to complete certain transactions, such as covering short sales, avoiding failures to deliver securities, or completing arbitrage operations. By lending its investment securities, a fund attempts to increase its net investment income through the receipt of interest on the securities lent. Any gain or loss in the market price of the securities lent that might occur during the term of the loan would be for the account of the fund. If the borrower defaults on its obligation to return the securities lent because of insolvency or other reasons, a fund could experience delays and costs in recovering the securities lent or in gaining access to the collateral. These delays and costs could be greater for foreign securities. If a fund is not able to recover the securities lent, the fund may sell the collateral and purchase a replacement investment in the market. The value of the collateral could decrease below the value of the replacement investment by the time the replacement investment is purchased. Cash received as collateral through loan transactions may be invested in other eligible securities. Investing this cash subjects that investment to market appreciation or depreciation. Currently, Vanguard funds that lend securities invest the cash collateral received in one or more Vanguard CMT Funds, which are low-cost money market funds.

The terms and the structure of the loan arrangements, as well as the aggregate amount of securities loans, must be consistent with the 1940 Act and the rules or interpretations of the SEC thereunder. These provisions limit the amount of securities a fund may lend to 33 1/3% of the fund’s total assets and require that (1) the borrower pledge and maintain with the fund collateral consisting of cash, an irrevocable letter of credit, or securities issued or guaranteed by the U.S. government having at all times not less than 100% of the value of the securities lent; (2) the borrower add to such collateral whenever the price of the securities lent rises (i.e., the borrower “marks to market” on a daily basis); (3) the loan be made subject to termination by the fund at any time; and (4) the fund receives reasonable interest on the loan (which may include the fund investing any cash collateral in interest-bearing short-term investments), any distribution on the lent securities, and any increase in their market value. Loan arrangements made by a fund will comply with all other applicable regulatory requirements, including the requirement to redeliver the securities within the standard settlement time applicable to the relevant trading market. The advisor will consider the creditworthiness of the borrower, among other things, in making decisions with respect to the lending of securities, subject to oversight by the board of trustees. At the present time, the SEC does not object if an investment company pays reasonable negotiated fees in connection with lent securities, so long as such fees are set forth in a written contract and approved by the investment company’s trustees. In addition, voting rights pass with the lent securities, but if a fund has knowledge that a material event will occur affecting securities on loan, and in respect to which the holder of the securities will be entitled to vote or consent, the lender must be entitled to call the loaned securities in time to vote or consent. A fund bears the risk that there may be a delay in the return of the securities, which may impair the fund’s ability to vote on such a matter.

Pursuant to Vanguard’s securities lending policy, Vanguard’s fixed income and money market funds are not permitted to, and do not, lend their investment securities.

Tax Matters—Federal Tax Discussion. Discussion herein of U.S. federal income tax matters summarizes some of the important, generally applicable U.S. federal tax considerations relevant to investment in a fund based on the IRC, U.S. Treasury regulations, and other applicable authorities. These authorities are subject to change by legislative, administrative, or judicial action, possibly with retroactive effect. Each Fund has not requested and will not request an advance ruling from the Internal Revenue Service (IRS) as to the U.S. federal income tax matters discussed in this Statement of Additional Information. In some cases, a fund’s tax position may be uncertain under current tax law and an adverse determination or future guidance by the IRS with respect to such a position could adversely affect the fund and its shareholders, including the fund’s ability to continue to qualify as a regulated investment company or to continue to pursue its current investment strategy. A shareholder should consult his or her tax professional for information regarding the particular situation and the possible application of U.S. federal, state, local, foreign, and other taxes.

Tax Matters—Federal Tax Treatment of Derivatives, Hedging, and Related Transactions. A fund’s transactions in derivative instruments (including, but not limited to, options, futures, forward contracts, and swap agreements), as well as any of the fund’s hedging, short sale, securities loan, or similar transactions, may be subject to one or more special tax rules that accelerate income to the fund, defer losses to the fund, cause adjustments in the holding periods of the fund’s securities, convert long-term capital gains into short-term capital gains, or convert short-term capital losses into long-term capital losses. These rules could therefore affect the amount, timing, and character of distributions to shareholders.

Because these and other tax rules applicable to these types of transactions are in some cases uncertain under current law, an adverse determination or future guidance by the IRS with respect to these rules (which determination or

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guidance could be retroactive) may affect whether a fund has made sufficient distributions, and otherwise satisfied the relevant requirements, to maintain its qualification as a regulated investment company and avoid a fund-level tax.

Tax Matters—Federal Tax Treatment of Futures Contracts. For federal income tax purposes, a fund generally must recognize, as of the end of each taxable year, any net unrealized gains and losses on certain futures contracts, as well as any gains and losses actually realized during the year. In these cases, any gain or loss recognized with respect to a futures contract is considered to be 60% long-term capital gain or loss and 40% short-term capital gain or loss, without regard to the holding period of the contract. Gains and losses on certain other futures contracts (primarily non-U.S. futures contracts) are not recognized until the contracts are closed and are treated as long-term or short-term, depending on the holding period of the contract. Sales of futures contracts that are intended to hedge against a change in the value of securities held by a fund may affect the holding period of such securities and, consequently, the nature of the gain or loss on such securities upon disposition. A fund may be required to defer the recognition of losses on one position, such as futures contracts, to the extent of any unrecognized gains on a related offsetting position held by the fund.

A fund will distribute to shareholders annually any net capital gains that have been recognized for federal income tax purposes on futures transactions. Such distributions will be combined with distributions of capital gains realized on the fund’s other investments, and shareholders will be advised on the nature of the distributions.

Tax Matters—Federal Tax Treatment of Non-U.S. Currency Transactions. Special rules generally govern the federal income tax treatment of a fund’s transactions in the following: non-U.S. currencies; non-U.S. currency-denominated debt obligations; and certain non-U.S. currency options, futures contracts, forward contracts, and similar instruments. Accordingly, if a fund engages in these types of transactions it may have ordinary income or loss to the extent that such income or loss results from fluctuations in the value of the non-U.S. currency concerned. Such ordinary income could accelerate fund distributions to shareholders and increase the distributions taxed to shareholders as ordinary income. Any ordinary loss so created will generally reduce ordinary income distributions and, in some cases, could require the recharacterization of prior ordinary income distributions. Net ordinary losses cannot be carried forward by the fund to offset income or gains realized in subsequent taxable years.

Any gain or loss attributable to the non-U.S. currency component of a transaction engaged in by a fund that is not subject to these special currency rules (such as foreign equity investments other than certain preferred stocks) will generally be treated as a capital gain or loss and will not be segregated from the gain or loss on the underlying transaction.

To the extent a fund engages in non-U.S. currency hedging, the fund may elect or be required to apply other rules that could affect the character, timing, or amount of the fund’s gains and losses. For more information, see “Tax Matters—Federal Tax Treatment of Derivatives, Hedging, and Related Transactions.”

Tax Matters—Foreign Tax Credit. Foreign governments may withhold taxes on dividends and interest paid with respect to foreign securities held by a fund. Foreign governments may also impose taxes on other payments or gains with respect to foreign securities. If, at the close of its fiscal year, more than 50% of a fund’s total assets are invested in securities of foreign issuers, the fund may elect to pass through to shareholders the ability to deduct or, if they meet certain holding period requirements, take a credit for foreign taxes paid by the fund. Similarly, if at the close of each quarter of a fund’s taxable year, at least 50% of its total assets consist of interests in other regulated investment companies, the fund is permitted to elect to pass through to its shareholders the foreign income taxes paid by the fund in connection with foreign securities held directly by the fund or held by a regulated investment company in which the fund invests that has elected to pass through such taxes to shareholders.

Tax Matters—Passive Foreign Investment Companies. Each Fund may invest in passive foreign investment companies (PFICs). A foreign company is generally a PFIC if 75% or more of its gross income is passive or if 50% or more of its assets produce passive income. Capital gains on the sale of an interest in a PFIC will be deemed ordinary income regardless of how long the Fund held it. Also, a Fund may be subject to corporate income tax and an interest charge on certain dividends and capital gains earned in respect to PFIC interests, whether or not such amounts are distributed to shareholders. To avoid such tax and interest, a Fund may elect to “mark to market” its PFIC interests, that is, to treat such interests as sold on the last day of the Fund’s fiscal year, and to recognize any unrealized gains (or losses, to the extent of previously recognized gains) as ordinary income each year. Distributions from a Fund that are attributable to income or gains earned in respect to PFIC interests are characterized as ordinary income.

Tax Matters—Real Estate Mortgage Investment Conduits. If a fund invests directly or indirectly, including through a REIT or other pass-through entity, in residual interests in real estate mortgage investment conduits (REMICs) or equity interests in taxable mortgage pools (TMPs), a portion of the fund’s income that is attributable to a residual interest in a

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REMIC or an equity interest in a TMP (such portion referred to in the IRC as an “excess inclusion”) will be subject to U.S. federal income tax in all events—including potentially at the fund level—under a notice issued by the IRS in October 2006 and U.S. Treasury regulations that have yet to be issued but may apply retroactively. This notice also provides, and the regulations are expected to provide, that excess inclusion income of a registered investment company will be allocated to shareholders of the registered investment company in proportion to the dividends received by such shareholders, with the same consequences as if the shareholders held the related interest directly. In general, excess inclusion income allocated to shareholders (1) cannot be offset by net operation losses (subject to a limited exception for certain thrift institutions); (2) will constitute unrelated business taxable income (UBTI) to entities (including a qualified pension plan, an individual retirement account, a 401(k) plan, a Keogh plan, or other tax-exempt entity) subject to tax on UBTI, thereby potentially requiring such an entity, which otherwise might not be required, to file a tax return and pay tax on such income; and (3) in the case of a non-U.S. investor, will not qualify for any reduction in U.S. federal withholding tax. A shareholder will be subject to U.S. federal income tax on such inclusions notwithstanding any exemption from such income tax otherwise available under the IRC. As a result, a fund investing in such interests may not be suitable for charitable remainder trusts. See “Tax Matters—Tax-Exempt Investors.”

Tax Matters—Tax Considerations for Non-U.S. Investors. U.S. withholding and estate taxes and certain U.S. tax reporting requirements may apply to any investments made by non-U.S. investors in Vanguard funds. Certain properly reported distributions of qualifying interest income or short-term capital gain made by a fund to its non-U.S. investors are exempt from U.S. withholding taxes, provided the investors furnish valid tax documentation (i.e., IRS Form W-8) certifying as to their non-U.S. status.

A fund is permitted, but is not required, to report any of its distributions as eligible for such relief, and some distributions (e.g., distributions of interest a fund receives from non-U.S. issuers) are not eligible for this relief. For some funds, Vanguard has chosen to report qualifying distributions and apply the withholding exemption to those distributions when made to non-U.S. shareholders who invest directly with Vanguard. For other funds, Vanguard may choose not to apply the withholding exemption to qualifying fund distributions made to direct shareholders, but may provide the reporting to such shareholders. In these cases, a shareholder may be able to reclaim such withholding tax directly from the IRS.

If shareholders hold fund shares (including ETF shares) through a broker or intermediary, their broker or intermediary may apply this relief to properly reported qualifying distributions made to shareholders with respect to those shares. If a shareholder’s broker or intermediary instead collects withholding tax where the fund has provided the proper reporting, the shareholder may be able to reclaim such withholding tax from the IRS. Please consult your broker or intermediary regarding the application of these rules.

This relief does not apply to any withholding required under the Foreign Account Tax Compliance Act (FATCA), which generally requires a fund to obtain information sufficient to identify the status of each of its shareholders. If a shareholder fails to provide this information or otherwise fails to comply with FATCA, a fund may be required to withhold under FATCA at a rate of 30% with respect to that shareholder on fund distributions and on the proceeds of the sale, redemption, or exchange of fund shares. Please consult your tax advisor for more information about these rules.

Tax Matters—Tax-Exempt Investors. Income of a fund that would be UBTI if earned directly by a tax-exempt entity will not generally be attributed as UBTI to a tax-exempt shareholder of the fund. Notwithstanding this “blocking” effect, a tax-exempt shareholder could realize UBTI by virtue of its investment in a fund if shares in the fund constitute debt-financed property in the hands of the tax-exempt shareholder within the meaning of IRC Section 514(b).

A tax-exempt shareholder may also recognize UBTI if a fund recognizes “excess inclusion income” derived from direct or indirect investments in residual interests in REMICs or equity interests in TMPs. See “Tax Matters—Real Estate Mortgage Investment Conduits.”

In addition, special tax consequences apply to charitable remainder trusts that invest in a fund that invests directly or indirectly in residual interests in REMICs or equity interests in TMPs. Charitable remainder trusts and other tax-exempt investors are urged to consult their tax advisors concerning the consequences of investing in a fund.

Time Deposits. Time deposits are subject to the same risks that pertain to domestic issuers of money market instruments, most notably credit risk (and, to a lesser extent, income risk, market risk, and liquidity risk). Additionally, time deposits of foreign branches of U.S. banks and foreign branches of foreign banks may be subject to certain sovereign risks. One such risk is the possibility that a sovereign country might prevent capital, in the form of U.S. dollars,

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from flowing across its borders. Other risks include adverse political and economic developments, the extent and quality of government regulation of financial markets and institutions, the imposition of foreign withholding taxes, and expropriation or nationalization of foreign issuers. However, time deposits of such issuers will undergo the same type of credit analysis as domestic issuers in which a Vanguard fund invests and will have at least the same financial strength as the domestic issuers approved for the fund.

Warrants. Warrants are instruments that give the holder the right, but not the obligation, to buy an equity security at a specific price for a specific period of time. Changes in the value of a warrant do not necessarily correspond to changes in the value of its underlying security. The price of a warrant may be more volatile than the price of its underlying security, and a warrant may offer greater potential for capital appreciation as well as capital loss. Warrants do not entitle a holder to dividends or voting rights with respect to the underlying security and do not represent any rights in the assets of the issuing company. A warrant ceases to have value if it is not exercised prior to its expiration date. These factors can make warrants more speculative than other types of investments.

When-Issued, Delayed-Delivery, and Forward-Commitment Transactions. When-issued, delayed-delivery, and forward-commitment transactions involve a commitment to purchase or sell specific securities at a predetermined price or yield in which payment and delivery take place after the customary settlement period for that type of security. Typically, no interest accrues to the purchaser until the security is delivered. When purchasing securities pursuant to one of these transactions, payment for the securities is not required until the delivery date. However, the purchaser assumes the rights and risks of ownership, including the risks of price and yield fluctuations and the risk that the security will not be issued as anticipated. When a fund has sold a security pursuant to one of these transactions, the fund does not participate in further gains or losses with respect to the security. If the other party to a delayed-delivery transaction fails to deliver or pay for the securities, the fund could miss a favorable price or yield opportunity or suffer a loss. A fund may renegotiate a when-issued or forward-commitment transaction and may sell the underlying securities before delivery, which may result in capital gains or losses for the fund. When-issued, delayed-delivery, and forward-commitment transactions will not be considered to constitute the issuance, by a fund, of a “senior security,” as that term is defined in Section 18(g) of the 1940 Act, and therefore such transaction will not be subject to the 300% asset coverage requirement otherwise applicable to borrowings by the fund, if the fund covers the transaction in accordance with the requirements described under the heading “Borrowing.”

SHARE PRICE

Multiple-class funds do not have a single share price. Rather, each class has a share price, called its net asset value, or NAV, that is calculated each business day as of the close of regular trading on the New York Stock Exchange (the Exchange), generally 4 p.m., Eastern time. NAV per share is computed by dividing the total assets, minus liabilities, allocated to the share class by the number of Fund shares outstanding for that class. On U.S. holidays or other days when the Exchange is closed, the NAV is not calculated, and the Funds do not sell or redeem shares. However, on those days the value of a Fund’s assets may be affected to the extent that the Fund holds securities that change in value on those days (such as foreign securities that trade on foreign markets that are open).

The Exchange typically observes the following holidays: New Year’s Day; Martin Luther King, Jr., Day; Presidents’ Day (Washington’s Birthday); Good Friday; Memorial Day; Independence Day; Labor Day; Thanksgiving Day; and Christmas Day. Although the Fund expects the same holidays to be observed in the future, the Exchange may modify its holiday schedule or hours of operation at any time.

PURCHASE AND REDEMPTION OF SHARES

Purchase of Shares

The purchase price of shares of each Fund is the NAV per share next determined after the purchase request is received in good order, as defined in the Fund’s prospectus.

Each Fund reserves the right at its sole discretion to impose a purchase fee if the purchase, in the opinion of the advisor, would disrupt the efficient management of the Fund. Lump-sum purchases may be considered disruptive, for example, if the advisor incurs significant transaction costs in purchasing securities needed to match the investment performance of the respective benchmark index. If such purchases can be offset by redemptions of shares by other shareholders, such

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fee may be waived or reduced. A prospective investor may determine whether a fee will be charged by calling their client representative or plan sponsor in advance of a purchase.

Exchange of Securities for Shares of a Fund. Shares of a Fund may be purchased “in kind” (i.e., in exchange for securities, rather than for cash) at the discretion of the Fund’s portfolio manager. Such securities must not be restricted as to transfer and must have a value that is readily ascertainable. Securities accepted by the Fund will be valued, as set forth in the Fund’s prospectus, as of the time of the next determination of NAV after such acceptance. All dividend, subscription, or other rights that are reflected in the market price of accepted securities at the time of valuation become the property of the Fund and must be delivered to the Fund by the investor upon receipt from the issuer. A gain or loss for federal income tax purposes, depending upon the cost of the securities tendered, would be realized by the investor upon the exchange. Investors interested in purchasing fund shares in kind should contact Vanguard.

Redemption of Shares

The redemption price of shares of each Fund is the NAV per share next determined after the redemption request is received in good order, as defined in the Fund’s prospectus.

Each Fund can postpone payment of redemption proceeds for up to seven calendar days. In addition, each Fund can suspend redemptions and/or postpone payments of redemption proceeds beyond seven calendar days (1) during any period that the Exchange is closed or trading on the Exchange is restricted as determined by the SEC; (2) during any period when an emergency exists, as defined by the SEC, as a result of which it is not reasonably practicable for the Fund to dispose of securities it owns or to fairly determine the value of its assets; or (3) for such other periods as the SEC may permit.

The Trust has filed a notice of election with the SEC to pay in cash all redemptions requested by any shareholder of record limited in amount during any 90-day period to the lesser of $250,000 or 1% of the net assets of a Fund at the beginning of such period.

If Vanguard determines that it would be detrimental to the best interests of the remaining shareholders of a Fund to make payment wholly or partly in cash, the Fund may pay the redemption price in whole or in part by a distribution in kind of readily marketable securities held by the Fund in lieu of cash in conformity with applicable rules of the SEC. Investors may incur brokerage charges on the sale of such securities received in payment of redemptions.

The Funds do not charge redemption fees. Shares redeemed may be worth more or less than what was paid for them, depending on the market value of the securities held by the Funds.

Right to Change Policies

Vanguard reserves the right, without notice, to (1) alter, add, or discontinue any conditions of purchase (including eligibility requirements), redemption, exchange, conversion, service, or privilege at any time; (2) accept initial purchases by telephone; (3) freeze any account and/or suspend account services if Vanguard has received reasonable notice of a dispute regarding the assets in an account, including notice of a dispute between the registered or beneficial account owners, or if Vanguard reasonably believes a fraudulent transaction may occur or has occurred; (4) temporarily freeze any account and/or suspend account services upon initial notification to Vanguard of the death of the shareholder until Vanguard receives required documentation in good order; (5) alter, impose, discontinue, or waive any purchase fee, redemption fee, account service fee, or other fees charged to a shareholder or a group of shareholders; and (6) redeem an account or suspend account privileges, without the owner’s permission to do so, in cases of threatening conduct or activity Vanguard believes to be suspicious, fraudulent, or illegal. Changes may affect any or all investors. These actions will be taken when, at the sole discretion of Vanguard management, Vanguard reasonably believes they are in the best interest of a fund.

Investing With Vanguard Through Other Firms

Each Fund has authorized certain agents to accept on its behalf purchase and redemption orders, and those agents are authorized to designate other intermediaries to accept purchase and redemption orders on the Fund’s behalf (collectively, Authorized Agents). The Fund will be deemed to have received a purchase or redemption order when an Authorized Agent accepts the order in accordance with the Fund’s instructions. In most instances, a customer order that

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is properly transmitted to an Authorized Agent will be priced at the NAV per share next determined after the order is received by the Authorized Agent.

MANAGEMENT OF THE FUNDS

Vanguard

Each Fund is part of the Vanguard group of investment companies, which consists of over 200 funds. Each fund is a series of a Delaware statutory trust, and through the trusts’ jointly owned subsidiary, Vanguard, the funds obtain at cost virtually all of their corporate management, administrative, and distribution services. Vanguard also provides investment advisory services on an at-cost basis to certain Vanguard funds.

Vanguard employs a supporting staff of management and administrative personnel needed to provide the requisite services to the funds and also furnishes the funds with necessary office space, furnishings, and equipment. Each fund (other than a fund of funds) pays its share of Vanguard’s total expenses, which are allocated among the funds under methods approved by the board of trustees of each fund. In addition, each fund bears its own direct expenses, such as legal, auditing, and custodial fees.

The funds’ officers are also employees of Vanguard.

Vanguard, Vanguard Marketing Corporation (VMC), the funds, and the funds’ advisors have adopted codes of ethics designed to prevent employees who may have access to nonpublic information about the trading activities of the funds (access persons) from profiting from that information. The codes of ethics permit access persons to invest in securities for their own accounts, including securities that may be held by a fund, but place substantive and procedural restrictions on the trading activities of access persons. For example, the codes of ethics require that access persons receive advance approval for most securities trades to ensure that there is no conflict with the trading activities of the funds.

Vanguard was established and operates under an Amended and Restated Funds’ Service Agreement. The Amended and Restated Funds’ Service Agreement provides that each Vanguard fund may be called upon to invest up to 0.40% of its net assets in Vanguard. The amounts that each fund has invested are adjusted from time to time in order to maintain the proportionate relationship between each fund’s relative net assets and its contribution to Vanguard’s capital.

As of December 31, 2017, each Fund had contributed capital to Vanguard as follows:

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Management. Corporate management and administrative services include (1) executive staff, (2) accounting and financial, (3) legal and regulatory, (4) shareholder account maintenance, (5) monitoring and control of custodian relationships, (6) shareholder reporting, and (7) review and evaluation of advisory and other services provided to the funds by third parties.

Distribution. Vanguard Marketing Corporation, 100 Vanguard Boulevard, Malvern, PA 19355, a wholly owned subsidiary of Vanguard, is the principal underwriter for the funds and in that capacity performs and finances marketing, promotional, and distribution activities (collectively, marketing and distribution activities) that are primarily intended to result in the sale of the funds’ shares. VMC offers shares of each fund for sale on a continuous basis and will use all reasonable efforts in connection with the distribution of shares of the funds. VMC performs marketing and distribution activities at cost in accordance with the conditions of a 1981 SEC exemptive order that permits the Vanguard funds to internalize and jointly finance the marketing, promotion, and distribution of their shares. The funds’ trustees review and approve the marketing and distribution expenses incurred by the funds, including the nature and cost of the activities and the desirability of each fund’s continued participation in the joint arrangement.

To ensure that each fund’s participation in the joint arrangement falls within a reasonable range of fairness, each fund contributes to VMC’s marketing and distribution expenses in accordance with an SEC-approved formula. Under that formula, one half of the marketing and distribution expenses are allocated among the funds based upon their relative net assets. The remaining half of those expenses are allocated among the funds based upon each fund’s sales for the preceding 24 months relative to the total sales of the funds as a group, provided, however, that no fund’s aggregate quarterly rate of contribution for marketing and distribution expenses shall exceed 125% of the average marketing and distribution expense rate for Vanguard and that no fund shall incur annual marketing and distribution expenses in excess of 0.20% of its average month-end net assets. Each fund’s contribution to these marketing and distribution expenses

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helps to maintain and enhance the attractiveness and viability of the Vanguard complex as a whole, which benefits all of the funds and their shareholders.

VMC’s principal marketing and distribution expenses are for advertising, promotional materials, and marketing personnel. Other marketing and distribution activities of an administrative nature that VMC undertakes on behalf of the funds may include, but are not limited to:

• Conducting or publishing Vanguard-generated research and analysis concerning the funds, other investments, the financial markets, or the economy.
• Providing views, opinions, advice, or commentary concerning the funds, other investments, the financial markets, or the economy.
• Providing analytical, statistical, performance, or other information concerning the funds, other investments, the financial markets, or the economy.
• Providing administrative services in connection with investments in the funds or other investments, including, but not limited to, shareholder services, recordkeeping services, and educational services.
• Providing products or services that assist investors or financial service providers (as defined below) in the investment decision-making process.
• Providing promotional discounts, commission-free trading, fee waivers, and other benefits to clients of Vanguard Brokerage Services^® who maintain qualifying investments in the funds.
• Sponsoring, jointly sponsoring, financially supporting, or participating in conferences, programs, seminars, presentations, meetings, or other events involving fund shareholders, financial service providers, or others concerning the funds, other investments, the financial markets, or the economy, such as industry conferences, prospecting trips, due diligence visits, training or education meetings, and sales presentations.

VMC performs most marketing and distribution activities itself. Some activities may be conducted by third parties pursuant to shared marketing arrangements under which VMC agrees to share the costs and performance of marketing and distribution activities in concert with a financial service provider. Financial service providers include, but are not limited to, investment advisors, broker-dealers, financial planners, financial consultants, banks, and insurance companies. Under these cost- and performance-sharing arrangements, VMC may pay or reimburse a financial service provider (or a third party it retains) for marketing and distribution activities that VMC would otherwise perform. VMC’s cost- and performance-sharing arrangements may be established in connection with Vanguard investment products or services offered or provided to or through the financial service providers. VMC’s arrangements for shared marketing and distribution activities may vary among financial service providers, and its payments or reimbursements to financial service providers in connection with shared marketing and distribution activities may be significant. VMC participates in an offshore arrangement established with a third party to provide marketing, promotional, and other services to qualifying Vanguard funds that are distributed in certain foreign countries on a private-placement basis to government-sponsored and other institutional investors. In exchange for such services, the third party receives an annual base (fixed) fee and may also receive discretionary fees or performance adjustments.

In connection with its marketing and distribution activities, VMC may give financial service providers (or their representatives) (1) promotional items of nominal value that display Vanguard’s logo, such as golf balls, shirts, towels, pens, and mouse pads; (2) gifts that do not exceed $100 per person annually and are not preconditioned on achievement of a sales target; (3) an occasional meal, a ticket to a sporting event or the theater, or comparable entertainment that is neither so frequent nor so extensive as to raise any question of propriety and is not preconditioned on achievement of a sales target; and (4) reasonable travel and lodging accommodations to facilitate participation in marketing and distribution activities.

VMC, as a matter of policy, does not pay asset-based fees, sales-based fees, or account-based fees to financial service providers in connection with its marketing and distribution activities for the Vanguard funds. VMC policy also prohibits marketing and distribution activities that are intended, designed, or likely to compromise suitability determinations by, or the fulfillment of any fiduciary duties or other obligations that apply to, financial service providers. Nonetheless, VMC’s marketing and distribution activities are primarily intended to result in the sale of the funds’ shares, and as such, its activities, including shared marketing and distribution activities, may influence participating financial service providers (or their representatives) to recommend, promote, include, or invest in a Vanguard fund or share class. In addition, Vanguard or any of its subsidiaries may retain a financial service provider to provide consulting or other services, and that financial service provider also may provide services to investors. Investors should consider the possibility that any of these

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activities or relationships may influence a financial service provider’s (or its representatives’) to recommend, promote, include, or invest in a Vanguard fund or share class. Each financial service provider should consider its suitability determinations, fiduciary duties, and other legal obligations (or those of its representatives) in connection with any decision to consider, recommend, promote, include, or invest in a Vanguard fund or share class.

The following table describes the expenses of Vanguard and VMC that are incurred by the Funds on an at-cost basis. Amounts captioned “Management and Administrative Expenses” include a Fund’s allocated share of expenses associated with the management, administrative, and transfer agency services Vanguard provides to the Vanguard funds. Amounts captioned “Marketing and Distribution Expenses” include a Fund’s allocated share of expenses associated with the marketing and distribution activities that VMC conducts on behalf of the Vanguard funds.

As is the case with all mutual funds, transaction costs incurred by the Funds for buying and selling securities are not reflected in the table. Annual Shared Fund Operating Expenses are based on expenses incurred in the fiscal years ended XX, and are presented as a percentage of each Fund’s average month-end net assets.

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Officers and Trustees

Each Vanguard fund is governed by the board of trustees of its trust and a single set of officers. Consistent with the board’s corporate governance principles, the trustees believe that their primary responsibility is oversight of the management of each fund for the benefit of its shareholders, not day-to-day management. The trustees set broad policies for the funds; select investment advisors; monitor fund operations, regulatory compliance, performance, and costs; nominate and select new trustees; and elect fund officers. Vanguard manages the day-to-day operations of the funds under the direction of the board of trustees.

The trustees play an active role, as a full board and at the committee level, in overseeing risk management for the funds. The trustees delegate the day-to-day risk management of the funds to various groups, including portfolio review, investment management, risk management, compliance, legal, fund accounting, and fund financial services. These groups provide the trustees with regular reports regarding investment, valuation, liquidity, and compliance, as well as the risks associated with each. The trustees also oversee risk management for the funds through regular interactions with the funds’ internal and external auditors.

The full board participates in the funds’ risk oversight, in part, through the Vanguard funds’ compliance program, which covers the following broad areas of compliance: investment and other operations; recordkeeping; valuation and pricing; communications and disclosure; reporting and accounting; oversight of service providers; fund governance; and codes of ethics, insider trading controls, and protection of nonpublic information. The program seeks to identify and assess risk through various methods, including through regular interdisciplinary communications between compliance professionals and business personnel who participate on a daily basis in risk management on behalf of the funds. The funds’ chief compliance officer regularly provides reports to the board in writing and in person.

The audit committee of the board, which is composed of JoAnn Heffernan Heisen, F. Joseph Loughrey, Mark Loughridge, Sarah Bloom Raskin, and Peter F. Volanakis, each of whom is an independent trustee, oversees management of financial risks and controls. The audit committee serves as the channel of communication between the independent auditors of the funds and the board with respect to financial statements and financial reporting processes, systems of internal control, and the audit process. Vanguard’s head of internal audit reports directly to the audit committee and provides reports to the committee in writing and in person on a regular basis. Although the audit committee is responsible for overseeing the management of financial risks, the entire board is regularly informed of these risks through committee reports.

All of the trustees bring to each fund’s board a wealth of executive leadership experience derived from their service as executives (in many cases chief executive officers), board members, and leaders of diverse public operating companies, academic institutions, and other organizations. In determining whether an individual is qualified to serve as a trustee of the funds, the board considers a wide variety of information about the trustee, and multiple factors contribute to the board’s decision. Each trustee is determined to have the experience, skills, and attributes necessary to serve the funds and their shareholders because each trustee demonstrates an exceptional ability to consider complex business and financial matters, evaluate the relative importance and priority of issues, make decisions, and contribute effectively to the deliberations of the board. The board also considers the individual experience of each trustee and determines that

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the trustee’s professional experience, education, and background contribute to the diversity of perspectives on the board. The business acumen, experience, and objective thinking of the trustees are considered invaluable assets for Vanguard management and, ultimately, the Vanguard funds’ shareholders. The specific roles and experience of each board member that factor into this determination are presented on the following pages. The mailing address of the trustees and officers is P.O. Box 876, Valley Forge, PA 19482.