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What triggered the sell-off?

Cerebras shares, which trade on Nasdaq, fell by about 20% on the week to their lowest level since the company’s May initial public offering. The stock ended Friday at $166.43, leaving it more than halfway below the strong gains seen after its market debut.

Weakness in the market was fueled by a Wednesday post on X from research firm SemiAnalysis. According to the post, OpenAI will use Nvidia graphics processors rather than Cerebras hardware for the “Ultrafast” mode of its GPT-6.1 Sol model. For investors looking for alternatives to Nvidia in AI infrastructure, the claim was seen as a blow to growth expectations.

What do the numbers say about market value?

Why is the OpenAI deal seen as critical?

Optimism that built after the company’s first trading day, when Cerebras closed with a market value of about $95 billion, has faded significantly. Cerebras now has a market capitalization of just above $39 billion.

Cerebras rents out its custom chips, built mainly for inference workloads, as cloud services from its own data centers. In January, the company signed a deal with OpenAI worth more than $10 billion that includes supplying 750 megawatts of compute power through 2028. That is why any potential loss of OpenAI workloads is being closely watched for its impact on revenue visibility and the company’s growth story.

  • The stock fell about 20% on the week.
  • Its market value was $95 billion on day one; the latest level is just above $39 billion.
  • The OpenAI deal is worth more than $10 billion and runs through 2028.

According to consulting firm McKinsey, inference workloads are expected to surpass training workloads in AI data centers toward the end of the decade. That outlook makes Cerebras’s business model even more sensitive in investors’ eyes.

How did the lock-up expiry and insider sales add pressure?

Beyond the OpenAI and Nvidia-related headlines, supply-side developments also weighed on the shares. According to the company’s prospectus, restrictions on 19.4 million shares held by executives, board members and other shareholders expired on Wednesday. That amount represents about 8% of the total shares outstanding.

Before that, up to 14.6 million shares had reportedly been eligible for sale every two weeks since Aug. 19. CEO Andrew Feldman and CTO Sean Lie sold more than $240 million of Class A shares between Aug. 20 and Sept. 25 under trading plans adopted shortly after the IPO. Several other executives also sold shares worth millions of dollars.

Sam Altman said in a post on X that "Cerebras is a close partner."

After Altman’s comment, the stock rose about 3% in after-hours trading on Friday. Still, that rebound has so far failed to offset the week’s sharp losses and the supply pressure created by the end of the lock-up period.

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