Cerebras Systems (CBRS) closed Monday at $181.55, up about 9% from Friday's $166.43. The jump followed a Friday post on X from OpenAI chief executive Sam Altman, who called the chipmaker "a close partner" and said the two have "a deep engagement pushing on the frontiers of speed".
Some of that gain faded on Tuesday. At 1:11 p.m. Eastern, the shares were about 2% lower at $177.11. Even at Monday's close, the stock was still below its $185 IPO price from May.
| Metric | Figure |
|---|---|
| Friday close (record closing low) | $166.43 |
| Monday close | $181.55 |
| Tuesday, 1:11 p.m. ET | $177.11 |
| IPO price (May 2026) | $185 |
| 52-week range | $160.81 to $386.34 |
| Market value | about $42 billion |
Figures from Yahoo Finance and Stock Analysis.
What Altman said, and what he left out
The sell-off started on Sept. 30. Research firm SemiAnalysis had said in a post on X that OpenAI's new GPT-6.1 Sol Ultrafast mode was running on Nvidia (NVDA) GPUs at small batch sizes, not on Cerebras hardware. Cerebras fell 7% that day and ended the week down nearly 20%.
Altman's post responded to "speculation" about the partnership. It didn't say which chips actually run Ultrafast. When Investing.com reported the drop, Cerebras hadn't made any public statement about the claim either. Barclays analyst Tom O'Malley read things this way: Nvidia is running Ultrafast, but Cerebras "remains the preferred provider limited by supply." He called the sell-off overdone. That's an analyst's interpretation. Neither company has confirmed it.
Why speed is the whole pitch
Cerebras doesn't cut a silicon wafer into many small chips. It uses the whole wafer as one processor. The company says its WSE-3 has 4 trillion transistors, 900,000 cores and 44GB of on-chip memory, and its chip page lists the same transistor and core counts for the current Turbo version. According to OfficeChai, the speed comes from holding a model's weights in that on-chip memory. Bigger models have to be split across several wafers, which makes them harder to run.
For ChatGPT users, that decides how fast an answer appears on screen. In August, OpenAI said GPT-5.6 Sol could reach up to 750 tokens per second on Cerebras. The GPU-based Ultrafast tier runs at about 300 tokens per second and costs six times the standard price, or $300 per million output tokens. Right now, faster answers cost more. Cerebras is betting that wafer-scale chips can bring that price down.
The contract is bigger than often reported
A lot of this week's coverage, including Yahoo Finance, cites a $10 billion OpenAI deal signed in January. FinanceFeeds traced that figure to a CNBC report from January, which put the deal at "over $10 billion". Cerebras' first quarter results release, filed with the SEC on June 23 as an exhibit to a Form 8-K, puts the deal at more than $20 billion, for 750 megawatts of inference computing over several years. In April, The Information reported that the deal had doubled and included warrants that could give OpenAI up to 10% of Cerebras if its spending reached $30 billion.
That cuts both ways. Cerebras has a bigger backlog, but more of its future rides on one customer. The forward-looking statements in that same June release list OpenAI, G42, Mohamed bin Zayed University of Artificial Intelligence and AWS as significant customers the company depends on. The release also guided to 2026 core revenue of $855 million to $865 million, so a contract worth more than $20 billion dwarfs its current sales.
The next scheduled catalyst is third-quarter results. Stock Analysis estimates they'll come on Nov. 19, but Cerebras hasn't confirmed a date in anything we've seen. Investors will be looking for the OpenAI share of revenue and any word on which models run on Cerebras hardware.
Until then, the only public account of which chips run Ultrafast is a research firm's post on X, and Altman's reply neither confirmed nor denied it.
Sources
- 1.OpenAI's Sam Altman calls Cerebras 'close partner' in speed, boosting chipmaker's stock · Seeking Alpha via TradingView
- 2.Cerebras Stock Surges After OpenAI CEO Calls Chipmaker a 'Close Partner' · Yahoo Finance
- 3.Cerebras stock slides as Nvidia reportedly powers OpenAI's 'Ultrafast' tier · Investing.com
- 4.OpenAI's GPT 6.1 Sol Ultrafast Is Not Running On Cerebras But On NVIDIA GPUs, Says Semi Analysis · OfficeChai
- 5.Cerebras Systems Form 8-K: first quarter 2026 financial results · U.S. Securities and Exchange Commission
- 6.OpenAI to spend more than $20 billion on Cerebras chips, receive stake, The Information reports · Yahoo Finance (Reuters report)
- 7.Cerebras Systems (CBRS) Stock Price & Overview · Stock Analysis
- 8.Cerebras WSE-3 chip · Cerebras Systems
- 9.Cerebras' stock slide stops after Sam Altman calls it 'close partner' · DigiTimes
- 10.Sam Altman on X: "There is some speculation about our partnership with Cerebras..." · X (Sam Altman)
- 11.Cerebras Systems Inc. (CBRS) Stock Quote · Yahoo Finance
- 12.SemiAnalysis on X: OpenAI's latest GPT6.1 Sol Ultrafast is NOT running on Cerebras · X (SemiAnalysis)
- 13.Premarket movers: Brazilian ADRs surge, Leslie's plunges · Investing.com
- 14.Cerebras Systems Unveils World's Fastest AI Chip with Whopping 4 Trillion Transistors · Cerebras Systems
- 15.Cerebras stock fell 20% to $166.43. The 3% bounce is not the $185 test · FinanceFeeds
Reported by the WattsUpNext desk from the sources linked below. Spot an error? Tell us at corrections@wattsupnext.com.
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