Cerebras stock pops 9% after Sam Altman calls the chipmaker a 'close partner'

Cerebras Systems' stock rose over 6% after OpenAI CEO Sam Altman affirmed a close partnership despite OpenAI choosing Nvidia GPUs for GPT-6.1 Sol's "Ultrafast" mode. Cerebras, which went public in May with a $95B valuation, now has a market cap around $39B and maintains a $10B deal with OpenAI for AI computing power through 2028.