Investing.com - U.S. stock index futures fell sharply on Monday, with technology stocks under pressure after several leading artificial intelligence executives called for a slower pace of AI development amid concerns over potential risks from the technology.

By 05:52 ET (09:52 GMT), the Dow futures contract had fallen 150 points, or 0.3%, S&P 500 futures had dropped 63 points, or 0.8%, and Nasdaq 100 futures had slumped 531 points, or 1.8%.

Here are some of the biggest premarket U.S. stock movers today:

Rumble shares surged as much as 28% in premarket trading after reports that Anthropic had agreed to a $13.7 billion computing contract with the company.

The Information reported that Anthropic entered into the deal with Rumble, which previously operated under the name Rumble. Rumble had disclosed a $13.7 billion contract in a securities filing in August but did not identify the customer at the time.

The deal comes as investors reassess the pace and risks of AI development. Anthropic CEO Dario Amodei called on AI companies to slow the advancement of model capabilities in an essay posted on X on Saturday, warning that increasingly capable AI agents could create significant economic damage if misused.

OpenAI CEO Sam Altman and xAI chief Elon Musk have also said they agree with Amodei’s concerns.

The comments weighed heavily on AI-linked stocks. Nvidia fell more than 2% in premarket trading, while Meta and Amazon each dropped more than 1%. Among chipmakers, Intel, AMD and Marvell Technology fell nearly 6%, 5% and 6%, respectively.

The selloff was more pronounced in the technology sector, as investors weighed whether a slower pace of AI development could affect spending on chips and data-center infrastructure.

Meanwhile, some U.S. software stocks moved higher as the broader AI selloff eased concerns that artificial intelligence could rapidly disrupt their businesses. ServiceNow, Adobe and Workday rose about 3%, 2.5% and 2.5%, respectively.

Scholar Rock shares surged 9.1% in premarket trading to $60.45 after the U.S. Food and Drug Administration approved ISEMBYLD (apitegromab-mstn) as the first and only muscle-targeted treatment for spinal muscular atrophy in adults and children aged two and older who are receiving an SMN2-targeted therapy.

The approval, announced after Friday’s close, came ahead of the September 30, 2026 PDUFA deadline. The broad label was in line with or better than expectations, according to the information provided, marking a major step for Scholar Rock as it moves from a clinical-stage developer to a commercial biopharmaceutical company.

Elmet Group shares jumped 30.8% in premarket trading after the company announced a $450 million committed investment from the U.S. Department of War.

The investment, announced before Monday’s opening bell, is intended to accelerate domestic tungsten manufacturing, reduce U.S. reliance on foreign sources of the critical mineral and expand Elmet Group’s mining and processing network across the U.S., Australia and Spain.

Olema Pharmaceuticals shares slid 15.1% in premarket trading to $8.68 after AstraZeneca announced late Friday that its Phase 3 SERENA-4 trial of camizestrant failed to demonstrate a statistically significant improvement in progression-free survival as a first-line treatment for ER-positive, HER2-negative advanced breast cancer.

The result is particularly significant for Olema because its lead candidate, palazestrant (OP-1250), is also a SERD/CERAN with a similar dual mechanism. Palazestrant is currently being evaluated in the pivotal OPERA-01 Phase 3 trial in a closely overlapping patient population, raising concerns about the prospects for Olema’s program.

MARA Holdings fell 5.7% in premarket trading to $11.30 after JPMorgan double-downgraded the bitcoin miner from Neutral to Underweight and cut its price target to $11 from $13, extending the target horizon to December 2027.

JPMorgan analysts raised concerns about MARA’s capital-light strategy through its joint venture with Starwood Digital Ventures. Under the arrangement, MARA contributes powered land sites while its partner handles design, development, tenant sourcing and operations. The analysts argued that MARA captures only about half of the value created, weighing on the company’s risk-reward profile.

The sharp decline in futures puts technology stocks in focus at the start of the week, with investors weighing the potential impact of a slower AI development cycle on chipmakers and other companies tied to the AI investment boom.