Cerebras stock falls below IPO price amid insider sales and doubts on key customer usage.

Cerebras Systems' stock dropped below its IPO price on September 30, 2026, coinciding with the end of its post-IPO lockup period and insider filings to sell shares worth over $84 million. The decline was also fueled by reports questioning whether OpenAI, a major customer, is using rival hardware for its latest ultrafast AI model instead of Cerebras systems. While Cerebras reported strong revenue growth, the stock's high valuation at 68 times trailing sales makes it vulnerable to concerns about customer concentration. Analysts remain optimistic but await clearer confirmation from OpenAI or Cerebras about hardware usage and insider sales details to assess future risks and stock stability.

Cerebras Systems trades with a market cap of $42.20 billion and a volume of 13,774,557 shares on Pluang as of October 1, 2026, 20:02 WIB. Despite the recent drop below its IPO price mentioned in the article, the stock is up 0.93% on Pluang at USD 179.30. Order activity shows a majority of 59% sell orders, indicating some investor caution following insider sales and customer concerns.