Cerebras Counters Short Seller: Wafers Qualify for 33 Years, Not Two

TSMC qualifies Cerebras's wafer-scale processor for 10 years of continuous operation at 105°C, CEO Andrew Feldman said on Nov. 5. An Arrhenius aging model at the chip's actual 85°C maximum stretches that to 33 years. That figure is the company's answer to short seller Culper Research, which claims the wafers wear out in 1.5 to 2.5 years.

"Nearly every financial conclusion in that report, from our margins to the value of our OpenAI agreement, depends on that one number," Feldman wrote. "That number is wrong."

What did Culper allege?

Culper Research disclosed a short position on Oct. 28. It argued the field lifespan of Cerebras chips runs only 1.5 to 2.5 years, and it alleged the company programs its wafers to run continuous "dummy operations" so they never cool. Cerebras shares fell about 6% in afternoon trading that day, Yahoo Finance reported, and the company did not respond at the time.

What does Cerebras's data show?

Feldman laid out the thermal case in detail:

• TSMC, which manufactures the wafer, qualifies it for 10 years of continuous operation at 105°C, 20 degrees above Cerebras's maximum.
• Across the deployed CS-3 fleet, average junction temperature sits below 65°C and never exceeds 85°C.
• The Arrhenius equation, the standard model for heat-driven chip aging, gives 33 years at a constant 85°C and more than a century at 65°C.

Feldman said Culper's model used neither a valid reference lifetime nor the actual operating temperature. Scaling the five-to-seven-year economic life of GPUs by a workload ratio, he wrote, "yields a number that describes nothing."

Feldman confirmed one part of the short thesis. Cerebras does hold its wafers at a steady temperature and uses controlled power draw — the "dummy operations" Culper described — to avoid abrupt swings that cause mechanical fatigue. He compared it to a "power burner" mode in Nvidia's B300 design. He denied the rest, stating Cerebras has never relied on PariPoser, a third-party connector material, and "never shipped a single system that uses it."

On accounting, Feldman said the useful life in Cerebras's first S-1 was 1 to 3 years because internal equipment was mainly R&D lab gear. It moved to 3 to 5 years once the company owned production systems for its cloud service. KPMG audits those estimates, he wrote. Culper had argued the change lengthened depreciation and lifted margins without explanation.

Does the data settle the dispute?

Not entirely, and Feldman admitted as much. Less than half of one percent of CS-3 wafers deployed since the 2024 launch have been decommissioned, according to the company. That record covers at most one to two years of service. Cerebras has not said how much of the fleet has run for more than two years, the exact window Culper's claim turns on. Feldman acknowledged that "there are not decades of data available" for a new architecture.

The rebuttal did move at least one skeptic. Tae Kim, a technology writer who said he had been bearish on the stock since its IPO, wrote that he believed Cerebras was right and was no longer negative on the shares at $83.

The market gets its next check soon. Cerebras reports third-quarter results after the market closes on Nov. 12, and the depreciation assumptions behind those margins will face their first test since the dispute began.