Cerebras shares fall 4% after Culper report questions chip lifespan and operation

Key Facts

Cerebras Systems shares fell 4% on Wednesday after Culper Research disclosed a short position and published a report criticizing the durability of the company’s processors and its technology, according to Investing.com coverage published on October 28. The report focuses on the field operating life of Cerebras’s large chips and on the method Culper says the company uses to keep them warm. The coverage quoted the report as estimating chip operating life at between 1.5 and 2.5 years. That means the criticism extends beyond Culper’s financial position to technical claims about product durability and how the chips are operated. Cerebras had not publicly responded to the report’s allegations when the coverage was published.

Culper questioned CEO Andrew Feldman’s account of developing a new conductor material to address thermal expansion, and said the company uses PariPoser, a material developed in the 1980s and sold by Paricon Technologies. This account appeared as part of the short seller’s thesis and was not independently verified by the coverage. The report also alleged that Cerebras programs its chips to run continuous dummy operations to keep them from cooling. Culper based this claim on remarks attributed to a company solutions engineer at the Café Compute event in Berlin in June 2026. The report thus combined questions about the conductor material in use with allegations that the chips are kept running continuously.

Culper said its reverse engineering of Cerebras software uncovered a field named “dummy tokens,” and the coverage said the company considered this field different from standard padding tokens. Investing.com reported that this detail formed part of the report’s reasoning for its claim that the chips perform operations that do not serve actual processing. These allegations remain attributed to Culper, which disclosed a short position, and the company had not publicly responded to them when the coverage was published. Separately, EL7 data shows CBRS closed at $119.31 on October 27. Public sources do not establish that the Culper report was issued after that close, and the decline cited in Wednesday’s coverage does not establish that the report alone caused the share move.

The allegations come as Cerebras had reported second-quarter total GAAP revenue of $180.1 million, up 74% year over year. GAAP revenue from cloud and other services was $126.0 million, up 281% from the same period a year earlier. In the same disclosure, the company reported a GAAP gross margin of 14%, compared with an underlying non-GAAP gross margin of 41%; the company said its underlying metrics exclude items including stock-based compensation and certain data center costs and revenue. The company also disclosed that one customer accounted for 34% of revenue in the second quarter, compared with 70% in the same period of 2025, while two customers accounted for 76% of accounts receivable on June 30. CEO Andrew Feldman said when announcing the results that underlying revenue more than doubled to $210 million and cloud activity came close to quadrupling from a year earlier.

According to Cerebras’s filing with the U.S. Securities and Exchange Commission, OpenAI committed to buying 750 megawatts of inference computing capacity and related services over several years. Cerebras also said remaining performance obligations totaled $25.4 billion on June 30, 2026. On October 27, the company and Oracle announced plans to make fast Cerebras inference available through Oracle Cloud Infrastructure. The company completed its IPO in May 2026 at $185 per share, and the stock began trading on Nasdaq on May 14; gross IPO proceeds totaled about $6.38 billion before costs. Cerebras scheduled its third-quarter results for after the market close on Thursday, November 12, 2026, with an earnings call at 5 p.m. Eastern Time that day; its published guidance for the quarter included underlying revenue of between $214 million and $216 million and an underlying operating margin of between negative 25% and negative 23%, and underlying revenue of between $880 million and $890 million for the fiscal year.