Cerebras Shares Rise 6.3% After Altman Reaffirms OpenAI Partnership

Cerebras shares were up 6.3% at $177 in premarket trading on October 5, 2026, after OpenAI CEO Sam Altman reaffirmed the companies’ partnership. The rebound followed a sharp sell-off over reports that Nvidia hardware would power an OpenAI model mode, putting Cerebras’s role with a major customer under scrutiny, CNBC reported.

The immediate concern was a specific hardware choice. CNBC reported that Nvidia graphics processing units, or GPUs, rather than Cerebras chips would power the “Ultrafast” mode for GPT-6.1 Sol. Cerebras shares fell 20% the previous week. That report concerned the mode’s hardware, not a disclosed cancellation of the broader OpenAI–Cerebras agreement.

Altman addressed the speculation in a Friday post on X, quoted by CNBC. Shares rose almost 3% in extended trading after his comments, before Monday’s premarket gain. His statement emphasized an ongoing relationship and work on speed, rather than identifying which hardware would serve the disputed mode.

Cerebras is a close partner, and we have a deep engagement pushing on the frontiers of speed.

Sam Altman, in a Friday X post quoted by CNBC

One mode versus a multiyear commitment

The existing agreement provides the scale behind that reassurance. In its January 14 announcement, Cerebras said the companies had signed a multiyear agreement to deploy 750 megawatts of its systems for OpenAI customers. The deployment was planned in multiple stages beginning in 2026. CNBC puts the deal’s value at $10 billion and says the supply commitment runs through 2028.

OpenAI’s explanation at the time described a mix of systems, not one hardware supplier for every task. In the Cerebras announcement, OpenAI’s Sachin Katti said its strategy was to build “a resilient portfolio that matches the right systems to the right workloads.” He described Cerebras as a dedicated solution for producing model responses with little delay.

Citi’s test is profitability, not reassurance

Citi analysts took a less alarmed view of the hardware news. In a Friday morning note quoted by CNBC, they said their outlook for Cerebras revenue from 2026 through 2028 remained unchanged. Their reasoning was about rollout order: they expected frontier AI labs’ newest models to appear on internal chips before third-party systems or Cerebras cloud.

That was an analyst expectation, not confirmation of a later Cerebras deployment for this mode. Citi’s more consequential warning concerned earnings quality: the analysts said the stock’s ability to outperform increasingly depended on evidence that gross margins were stabilizing. A further delay in the margin trough could weigh on sentiment, particularly given Cerebras’s premium valuation.

The rebound still left a substantial valuation gap. CNBC put Cerebras’s market capitalization at just over $39 billion, compared with $95 billion during its May debut. Monday’s early gain therefore came against a much larger retreat from the company’s initial public offering.