OpenAI acquired 4.2% of Cerebras before GPT-5.6 Ultrafast launch

Why it matters

OpenAI now has a multibillion-dollar economic interest in the chip supplier powering its fastest GPT-5.6 tier, aligning compute purchases with equity upside while leaving Cerebras shareholders exposed to further dilution.

Correction: An earlier version incorrectly described GPT-5.6 Sol Ultrafast as the first visible product deployment under the OpenAI-Cerebras relationship. OpenAI launched Cerebras-powered GPT-5.3-Codex-Spark in February and called it the partnership's first milestone. The story has been corrected.

The OpenAI-Cerebras partnership and its warrant agreement were already public. The new disclosure is that OpenAI exercised every Cerebras warrant share that had vested, acquiring a 4.22% economic stake in July, weeks before the companies introduced a Cerebras-powered service tier for GPT-5.6 Sol on Thursday.

Cerebras revealed the previously unreported exercise under "Subsequent Events" on page 29 of its quarterly filing, filed after the market closed on August 12th. OpenAI exercised warrants for 10,033,508 Class N shares at a contractual price of $0.00001 apiece, making the cash exercise cost approximately $100.34.

The stake puts OpenAI on both sides of one of the AI industry's largest infrastructure contracts: It is buying Cerebras compute while holding equity that gains value as Cerebras delivers against the agreement. Cerebras co-founder and CEO Andrew Feldman, who previously led microserver maker SeaMicro through its acquisition by AMD, has spent a decade building wafer-scale processors as an alternative to conventional GPU clusters.

Those shares represented 4.22% of Cerebras's 237,564,041 outstanding shares as of August 5th. Using Cerebras's publicly traded Class A stock price of about $229 on Thursday afternoon, the nonvoting stake carried an implied value of approximately $2.3 billion. That is a mark based on the Class A trading price, rather than the price of a liquid Class N security.

Class N shares have the same dividend and liquidation rights as Cerebras's Class A and Class B stock, according to the filing. They carry no votes and generally convert one-for-one into Class A shares when transferred. OpenAI therefore obtained substantial economic exposure without receiving a vote over Cerebras's board or corporate decisions.

OpenAI exercised every vested share

The warrant dates to Cerebras's December 2025 master relationship agreement with OpenAI. The agreement committed OpenAI to buy 750 megawatts of inference capacity, scheduled for deployment in tranches through 2028, and gave OpenAI an option for another 1.25 gigawatts by the end of 2030. OpenAI also provided Cerebras with a secured working-capital loan of approximately $1 billion in January.

The full warrant covers 33,445,026 Class N shares. A tranche of 4,459,337 shares vested in January after OpenAI funded the loan, and another 5,574,171 shares vested in June. The sum of those tranches is exactly the number OpenAI exercised in July. Cerebras had reported that none of the vested warrants had been exercised as of June 30th.

The nominal strike price reflects the warrant's role as a commercial incentive, rather than an ordinary investment at prevailing market value. Cerebras valued the warrant at $82.02 per share when it was granted and records the resulting customer warrant asset as a reduction in revenue over the life of the customer relationship. Cerebras recorded $822.9 million in OpenAI customer warrant assets during the first half of 2026.

That accounting treatment captures the bargain's economic structure. Cerebras receives a large, long-duration buyer for infrastructure that requires heavy upfront spending. OpenAI receives low-latency compute, a $2.3 billion paper stake based on Thursday's market price, and the possibility of substantially greater ownership if the relationship expands.

Another 23.4 million shares remain available

OpenAI retains warrants for 23,411,518 additional Cerebras shares. Their vesting depends on further milestones tied to committed and additional capacity, market capitalization or customer payments. Cerebras said in the filing that the remaining tranches associated with additional capacity were not considered probable of vesting as of June 30th.

If every remaining share vested and OpenAI exercised the warrants, OpenAI would own about 12.8% of Cerebras on the current share base after accounting for the new issuance, before any other dilution. The exercise cost for all 23.4 million remaining shares would be roughly $234.

That contingent upside gives OpenAI an economic interest in Cerebras meeting delivery targets and expanding the amount of compute that OpenAI buys. It also means Cerebras shareholders face additional dilution as the commercial relationship succeeds.

The product connection became explicit on August 13th. Cerebras and OpenAI launched GPT-5.6 Sol Ultrafast in limited preview, promising output of up to 750 tokens per second and speeds of up to 14 times the standard processing tier. Cerebras attributes the performance to its Wafer-Scale Engine architecture, which keeps model weights in on-chip memory rather than repeatedly moving them between processors and external memory.

The launch brings Cerebras inference to OpenAI's flagship frontier model, expanding a relationship OpenAI announced in January that first reached users in February with GPT-5.3-Codex-Spark. The July warrant exercise shows that OpenAI's exposure to Cerebras had already moved beyond a contractual right by the time Ultrafast reached customers: OpenAI was a 4.2% owner.

The stake could matter in any future M&A discussion, but the filing offers no evidence of takeover talks or intent. The disclosed structure is more directly explained by the companies' commercial agreement: nonvoting equity awarded through warrants tied to financing and capacity milestones.