Form DEFA14A Seer, Inc.

Preliminary Proxy Statement

Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

Definitive Proxy Statement

Definitive Additional Materials

Soliciting Material Pursuant to §240.14a-12

No fee required.

Fee paid previously with preliminary materials.

Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

Seer has pioneered a new market for deep, unbiased proteomics and is now uniquely positioned to power the next era of AI-driven precision medicine.

Category-leading technology capable of delivering significantly more data to train foundation models and reveal deeper insights than other proteomic platforms

Landmark population-scale studies and strategic collaborations are already underway, marking an acceleration point in Seer’s commercial opportunity

Robust innovation pipeline, including next-generation detector, has potential to meaningfully expand the end market for proteomics beyond mass spectrometry users

Substantial and fast-growing proteomics market could reach $23 billion total addressable market opportunity by 2034¹

Seer is delivering demonstrable progress against the goals outlined at its IPO despite a sector-wide downturn, and the Company’s commercial inflection point is now approaching.

Focus on cost discipline has led to meaningful reductions in SG&A and R&D expenses each year since 2023 and 36% decrease in annual cash burn² since 2022

Installed base has grown at a 62% CAGR since 2021, ³ supported by partnerships with every major mass spectrometry platform

Cumulative publications doubled over the last year for a total of 84 peer-reviewed publications since 2022,⁴ underscoring scientific community’s confidence in the platform

Product launches since 2021 have already increased platform throughput by ~10x, with additional launches on the horizon

With over 235 patent applications and issued patents, Seer is the leader in the category it created, and as industry validation continues to grow, the Company is ready to scale

Source: Canaccord Genuity Initiation of Coverage as of May 4, 2026

Based on 2025 cash burn; Cash burn represents cash flow from operations minus net capital expenditure

Source: Company filings as of March 31, 2026 and Company data

Source: Company Filings, Company Website as of May 13, 2026

Seer’s highly qualified, independent Board is actively engaged and accountable to advancing stockholders’ best interests.

Directors bring deep, highly relevant healthcare industry experience and life science tools expertise, and a majority also have financial backgrounds

Five of seven directors are independent, and average tenure of 5.5 years⁵ reflects commitment to ongoing refreshment

Directors collectively own 17% of Seer’s total shares outstanding⁶

Board has a clear track record of returning capital and protecting stockholder interests, including:

Authorizing $50 million in total share repurchases, with $25.5 million remaining in the program;⁷

Overseeing ~75% decrease in stock-based compensation since 2023 to annualized run rate of $8.5M in 2026;

Maintaining cash position of ~$220 million with no debt, providing ample runway to fund platform commercialization; and

Adopting a tax benefit preservation plan to ensure $262.4 million of federal net operating loss carryforwards remain available to benefit stockholders long term⁸

Bradley Radoff and Michael Torok are running a self-interested campaign to force an early sale of the Company and strip it of its own cash.

Campaign lacks actionable ideas for value creation

Radoff and Torok lack credibility as potential buyers, providing no evidence of committed financing or indicating any desire to put their own capital at risk

The Board carefully reviewed, discussed and unanimously rejected all of Radoff and Torok’s proposals in consultation with its independent financial and legal advisors

Radoff and Torok are seeking to replace highly qualified members of Seer’s Board with nominees who bring no relevant expertise or experience.

Proposed nominees bring no proteomics, life sciences instrumentation or operating expertise – only M&A experience

Long-standing ties to Radoff raise concerns about independence

Radoff and Torok declined to make nominees available for interviews, despite offers from the Board

Replacing existing directors with proposed nominees would remove invaluable expertise from Seer’s boardroom at a critical time in the Company’s growth trajectory

Source: Seer definitive proxy as of June 3, 2026

Total shares outstanding as of May 11, 2026

10-Q as of March 31, 2026

10-K as of December 31, 2025