Micron Technology, Inc. MU

The business

Micron makes memory chips. DRAM is the working memory a processor reads and writes constantly; NAND is the storage that keeps data when the power goes off. It is one of three companies in the world that make DRAM at scale.

Memory has always been the most brutally cyclical business in semiconductors because the product is interchangeable and the factories cost tens of billions. What has changed is that training an artificial-intelligence model requires enormous quantities of high-bandwidth memory stacked next to the accelerator, and that demand arrived faster than anyone could build capacity.