Intel plunged 45% in October, pressured by both weak PC business and a crisis of confidence among foundry customers.

November 3 — Intel's stock price suffered a historic plunge, falling 45% cumulatively in October, marking the company's worst monthly performance on record. On the last trading day of October, the stock plummeted 29% in a single day, the largest one-day drop since the 1970s, and fell another 8% on the first trading day of November.

The decline was primarily driven by a profit warning. Intel expects revenue for the current quarter to be $1 billion to $2 billion below analyst expectations, citing weak PC market demand and high costs for memory and other components. The PC business still accounts for about half of the company's revenue.

Meanwhile, although Intel's data center business continues to grow, insufficient capacity has forced the company to shift some production at its Oregon facility from the advanced 18A process to the Intel 3 process to increase server CPU supply. This adjustment has also raised concerns about its advanced process capacity and foundry delivery capabilities.

Harvard Business School professor David Yoffie warned that if Intel cannot provide sufficient capacity beyond meeting its own needs, it will be difficult for the company to become a trusted foundry supplier. Intel CEO Pat Gelsinger, meanwhile, said he expects to announce several foundry customers in the next two quarters, and that customer expansion progress will be key to its foundry business transformation.