Sam Altman Called Cerebras a 'Close Partner' and Stopped a 20% Slide
Four sentences from OpenAI's CEO lifted Cerebras stock 6.3% in premarket trading. The margin numbers still need to improve before the rally means anything.
Key points
- Cerebras stock rose 6.3% in premarket trading on Monday, 13 October 2026, to $177 per share after OpenAI CEO Sam Altman publicly called the company a "close partner."
- Shares had fallen roughly 20% the previous week once it emerged that OpenAI's "Ultrafast" mode inside GPT-6.1 Sol runs on Nvidia chips, not Cerebras chips.
- A $10 billion supply agreement signed with OpenAI in January 2026 covers 750 megawatts of computing through 2028 and has not been reported as changed.
- At $177, Cerebras trades at nearly half its post-IPO peak; its market cap sits just above $39 billion, down from $95 billion at its May 2026 Nasdaq debut.
- Citi analysts left their 2026 to 2028 revenue outlook unchanged but warned the stock's premium depends on evidence that gross margins are stabilising.
One week Cerebras was the hottest name in AI hardware. The next, it had lost a fifth of its value. Four sentences from Sam Altman stopped the bleeding.
Altman posted on X on Friday, 10 October, saying there was "some speculation" about OpenAI's relationship with Cerebras and that the company is "a close partner" with whom OpenAI has "a deep engagement pushing on the frontiers of speed." Shares rose almost 3% in extended trading that day, then added a further 6.3% in premarket Monday, first reported by CNBC Tech.
Why did Cerebras fall so sharply in the first place?
OpenAI chose Nvidia's GPUs, the specialised chips that handle AI's heavy computation, to run the "Ultrafast" mode of GPT-6.1 Sol. Cerebras had positioned itself as the faster alternative, and investors read the omission as a demotion.
Its flagship product, the Wafer Scale Engine 3 (WSE-3), packs an entire silicon wafer into a single chip rather than cutting it into smaller pieces. The company says this design lets it run AI models faster than conventional GPU setups. The $10 billion OpenAI deal signed in January 2026 seemed to confirm that pitch, which made the Nvidia reveal hit harder. The drop pushed Cerebras to its lowest price since going public in May 2026.
AI2Day first covered Cerebras on 15 July 2026; this is the third Cerebras story we have published.
What the analysts actually said
Citi kept its revenue outlook for Cerebras unchanged across 2026 to 2028. The bank argued that frontier AI labs, meaning companies building the most advanced AI systems, typically debut new models on in-house chips before moving workloads to outside suppliers. Reading a single product launch as a strategic retreat, Citi said, is too early.
The caution came in the same note. Citi told clients the stock's ability to outperform is "increasingly tied to evidence that gross margins are stabilising." Gross margins, the share of revenue left after direct production costs, have been under pressure. Any further delay in improving them, the bank added, would weigh on sentiment given Cerebras' premium valuation.
At $39 billion in market cap, the premium is real. Altman's post bought time. The margin trajectory is what actually matters now.
OpenAI itself has had a rough few weeks beyond hardware. We reported on a safety writer quitting publicly at /story/openai-safety-writer-quits-and-calls-out-the-company-publicly and on three researchers fired for mishandling sensitive information. Every public word from Altman lands in that context.
Common questions
Does this affect people who use ChatGPT or GPT-6.1 Sol?
No. Which company's chips run the model behind the scenes is invisible to users; the product experience is the same either way.
Is the OpenAI-Cerebras deal still active?
Yes. The $10 billion supply agreement signed in January 2026 runs through 2028 and has not been reported as changed or cancelled.
