Why Is Cerebras Systems (CBRS) Stock Down 8.87% Today, Sep 30? OpenAI-Nvidia Shift and Share Unlock Raise Selling Pressure

Cerebras (NCSKCBRS2USD) sold off after a 19.4M-share lockup release expanded near-term tradable supply, amplifying selling pressure. Separately, reports that OpenAI's new ultrafast inference mode is running on Nvidia GPUs raised concerns about Cerebras' future share of OpenAI inference workloads, a key valuation pillar given the large multi-year contract and backlog. The combination is a company-specific negative catalyst with potential spillover to AI hardware sentiment.