On 2 October 2026 Sam Altman wrote that speculation had emerged around the OpenAI partnership with Cerebras, and called Cerebras a "close partner" with which OpenAI is working deeply on increasing speed. Altman post

On 2 October 2026 Sam Altman wrote that speculation had emerged around the OpenAI partnership with Cerebras, and called Cerebras a "close partner" with which OpenAI is working deeply on increasing speed. Altman post

The trigger was reports citing SemiAnalysis: that GPT-6.1 Sol Ultrafast mode runs on a small batch with Nvidia GPUs, and not on Cerebras chips. In the found publications this claim is retold, but Altman himself did not confirm on which hardware this mode runs; his post confirms close collaboration in general, and not the specific role of Cerebras in GPT-6.1 Sol. Retelling of the report