Cerebras Stock Hits Post-IPO Low as Nvidia Claims OpenAI Inference Deal and Lockup Shares Flood Market

Cerebras Systems stock tumbled nearly 20% this week to its lowest point since the company's May debut on the Nasdaq, after reports emerged that Nvidia will power a key portion of OpenAI's latest AI model rather than Cerebras hardware — a blow compounded by an expiring lockup period that sent additional insider shares onto the market.

Research firm SemiAnalysis posted on X on Wednesday that OpenAI will use Nvidia graphics processing units to power the "Ultrafast" mode of its GPT-6.1 Sol model, a workload that had been associated with Cerebras. The stock closed Friday at $166.43, leaving Cerebras down more than 50% from the opening-day price that followed its May 14 IPO.

The company's market capitalization now sits at just over $39 billion, a steep decline from the $95 billion valuation it carried on its first day of trading — a figure that placed it just short of the $100 billion club occupied by Meta, Alibaba, and SpaceX at their respective market debuts.

The stock did recover some ground after market close, rising nearly 3% in extended trading Friday after OpenAI CEO Sam Altman addressed what he called "speculation about our partnership with Cerebras." "Cerebras is a close partner, and we have a deep engagement pushing on the frontiers of speed," Altman wrote in a post on X.

The sell-off was also driven by the expiration of post-IPO lockup restrictions. According to the company's prospectus, up to 19.4 million shares — equal to 8% of total shares outstanding — held by directors, officers, non-executive employees, and non-employee holders unlocked on Wednesday. Prior to that, up to 14.6 million shares had been released for sale every two weeks since August 19.

CEO Andrew Feldman and CTO Sean Lie, both of whom became billionaires through the IPO process, sold more than $240 million worth of Class A shares between August 20 and September 25 under trading plans adopted shortly after the company went public. Other executives have also sold shares valued in the millions.

Cerebras had generated significant investor enthusiasm at its IPO on the promise of offering an alternative to Nvidia for AI infrastructure. The company makes large custom chips designed specifically for inference workloads and leases computing capacity from its own data centers as a cloud service. In January, Cerebras struck a deal valued at over $10 billion with OpenAI to supply 750 megawatts of computing power through 2028.

Losing a visible inference workload to Nvidia has raised questions about that relationship's scope, underscoring the competitive pressure Cerebras faces from the dominant chipmaker even as its partnership with OpenAI formally remains intact.

The timing adds additional weight to the stock's slide. According to McKinsey, inference is expected to surpass training as the dominant workload in AI data centers by the end of the decade — making any perceived shift in that market particularly consequential for a company whose entire business model is built around it.

With more lockup tranches likely to expire in the months ahead, and broader questions remaining about the division of OpenAI's workloads between Cerebras and Nvidia, investors will be watching closely for any formal clarification from either company about the terms and scope of their respective agreements.

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