Advanced Micro Devices and Super Micro Computer led a selloff in chip stocks on Wednesday after their earnings disappointed investors who had piled into the sector on optimism about AI.AMD slumped nearly 10% and was on course to lose more than $21 billion in market value.

Artificial intelligence is expensive for the companies buying AI chips, and it’s expensive for the companies making them, too.

AMD ( AMD) , which is attempting to carve into market leader Nvidia's ( NVDA) 80% share of the market for artificial-intelligence-focused data-center chips, has seen demand for some of its traditional server chips wane amid the rush to secure higher-end processors.