Rigetti Computing, IonQ, and other quantum stocks plunged after Nvidia CEO Jensen Huang told Wall Street analysts that “very useful quantum computers” are likely 20 years away.

The quantum computing rally came to an abrupt end on Wednesday following comments from Nvidia CEO Jensen Huang. During a question-and-answer session with analysts, Huang put forth a more pessimistic view of the quantum computing timeline:

Nvidia CEO's comments on quantum computing caused a market drop, erasing $8 billion from companies like IonQ, Rigetti, and D-Wave. Huang suggested useful quantum computing may be 15-30 years away. D-Wave's CEO disagreed,