Cerebras Jumps 6.3% to $177 on Altman 'Close Partner' Call

For investors, Altman's eleventh-hour vote of confidence is a volatility event more than a fundamental fix. The $10 billion OpenAI contract underpins Cerebras' revenue story, but Citi's unchanged 2026-2028 outlook comes with a blunt warning: margin stabilization, not partnerships, will determine whether this premium valuation holds.

In early October 2026, OpenAI CEO Sam Altman intervened to stabilize one of the most volatile AI hardware names in the public market, calling Cerebras Systems a "close partner" and emphasizing that the two companies are engaged in deep work on speed. The comment, posted on X on Friday October 2, came just days after Cerebras shares had fallen 20% to their lowest level since the company's May Nasdaq debut. The selloff was triggered by news that OpenAI would run GPT-6.1 Sol's "Ultrafast" mode on Nvidia graphics processing units rather than Cerebras' wafer-scale chips. Altman's reassurance had an immediate effect: Cerebras was up nearly 3% in extended trading Friday, and by premarket Monday October 5 it was up 6.3% at $177 per share. Still, that left the company's market capitalization just over $39 billion, down from roughly $95 billion at its post-IPO high.

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Altman's reassurance had an immediate effect: Cerebras was up nearly 3% in extended trading Friday, and by premarket Monday October 5 it was up 6.3% at $177 per share.

The stakes for Cerebras are substantial. The company is one of the most prominent Nvidia competitors, selling large computer chips and AI systems designed to run models faster than traditional GPUs. Its flagship Wafer Scale Engine 3 is claimed to outperform Nvidia GPUs in certain tasks. That differentiating pitch helped Cerebras secure a landmark $10 billion deal with OpenAI in January 2026 to supply 750 megawatts of computing power through 2028. The agreement gave investors a tangible anchor for long-term revenue growth, but it also made Cerebras highly sensitive to any signal that OpenAI might prefer Nvidia for key workloads. Reports that Ultrafast, a speed-critical mode, would rely on Nvidia GPUs therefore cut directly at the core investment thesis.

Sam Altman's Friday post attempted to reframe the narrative: "There is some speculation about our partnership with Cerebras. Cerebras is a close partner, and we have a deep engagement pushing on the frontiers of speed." By emphasizing speed, Altman linked Cerebras to exactly the area where its architecture is supposed to shine. The rebuke to speculation was important because it implied the Nvidia decision was not a replacement of Cerebras but a workload-specific choice. In that reading, OpenAI is running a multi-vendor inference strategy, using Nvidia for some model modes and Cerebras for others, rather than shifting entirely away from the chipmaker.

Citi analysts offered a measured interpretation. They said their revenue outlook for Cerebras from 2026 to 2028 remains "unchanged," reasoning that frontier AI labs would initially roll out latest models on internal chips before turning to third-party cloud or Cerebras. Since this early rollout is consistent with prior assumptions, the Nvidia news did not warrant a cut to estimates. At the same time, Citi cautioned that the stock's ability to outperform is "increasingly tied to evidence that gross margins are stabilizing." Any further delay in the gross margin trough would likely weigh on sentiment, particularly given Cerebras' premium valuation. This dual message—revenue untouched but margins critical—captures the tension between the partnership's top-line promise and its financial execution.