Quantum computing stocks are tumbling after Nvidia CEO Jensen Huang warned that the technology is a long way off.

Quantum computing stocks sank on Wednesday, pausing a year-long rally, after Nvidia CEO Jensen Huang said the technology's practical use was likely two decades away. The long wait outlined by Huang for "very useful quantum computers" throws cold water on a sector that was already expected to spend millions more on the technology,

Quantum computing stocks took a dive Wednesday after investors' perceptions about the outlook for the sector were dramatically corrected. Valuations in the nascent space had been