Key Highlights

● Cerebras climbed after OpenAI CEO Sam Altman described the company as "a close partner" on social media.

● Cerebras signed a $10 billion agreement with OpenAI in January 2026 for 750 megawatts of computing capacity through 2028.

● The stock had been weak since disappointing Earnings in mid-August, making the comment especially notable.

Cerebras Systems climbed on Monday after OpenAI chief executive Sam Altman publicly described the AI chipmaker as "a close partner," easing chatter about the relationship.

Praise from Altman

Cerebras Systems (NASDAQ:CBRS) climbed on Monday, Oct. 5, gaining ground on the Nasdaq Composite after OpenAI CEO Sam Altman offered public praise on social media. Altman described Cerebras as "a close partner" of OpenAI.

Reports differed on the size of the rally, but every account agreed on the direction: up.

Reports said Altman's comments eased speculation about the state of the relationship between the two companies. That mattered, because the stock had been weak since disappointing earnings in mid-August.

Why OpenAI matters so much to Cerebras

Cerebras builds very large AI processors and computing systems designed to run artificial-intelligence models at high speed. For a young public company, a marquee customer can define the Investment story, and OpenAI is a marquee name on its roster.

Cerebras signed a $10 billion agreement with OpenAI in January 2026 to provide 750 megawatts of computing capacity through 2028. Any hint that the Partnership was cooling would have been a serious concern for investors. Altman's public words of support pushed in the other direction.

The stock is a recent initial public offering, so it has a short trading history and can move sharply on news about its biggest relationships.

AI Leadership drove the record

Cerebras was riding a strong tide. AI stocks once again carried the market higher on Monday. Nvidia (NASDAQ:NVDA) rose to a record close of about $238.90, giving it a Market Value of about $5.76 trillion, and the Associated Press called the chipmaker "the single strongest force lifting the S&P 500." Broadcom (NASDAQ:AVGO) rose, and Microsoft (NASDAQ:MSFT) gained after Melius Research upgraded it to Buy.

The Nasdaq Composite rose 286.45 points to a record 27,477.31, and the Nasdaq-100 set its own record at 31,076.44. The S&P 500 added 51.23 points to 7,773.95, just shy of its summer high, while the Dow rose 90.94 points to 51,267.90.

The rally was narrow under the surface, though. The Nasdaq logged 57 new highs against 243 new lows, a sign that big AI names were doing much of the heavy lifting.

Rates still loom

The macro picture is mixed. Friday's jobs report showed just 29,000 new payrolls in September, which cooled bets on another Federal Reserve rate hike in October. Yet the 10-year Treasury Yield climbed to its highest level since 2002, and Monday's ISM services survey showed prices paid at their highest since July 2022.

Capital.com's Daniela Hathorn captured the push and pull: "growth stocks are rallying because Fed expectations have softened, while the Risk-Free Rate against which those valuations are judged remains exceptionally high."

For AI hardware names like Cerebras, which are valued on future growth, that rate backdrop is a constant headwind even on good days.

What to watch

The next big test for Cerebras is its own quarterly report, where investors will look for signs that the OpenAI agreement is translating into Revenue and that the softness after mid-August earnings is behind it.

Elsewhere in AI chips, Elon Musk confirmed early talks with TSMC (NYSE:TSM) about his Terafab venture, saying: "Just discussions, but something may come of it." On the macro calendar, the Federal Reserve releases minutes of its September meeting on Wednesday, Oct. 7, at 2 p.m. ET, ahead of its Oct. 27–28 meeting. Earnings season ramps up with PepsiCo on Thursday, Delta Air Lines on Friday and the big banks from Oct. 13.