The emergence of DeepSeek is casting doubt on the power needs of AI—and on the stocks of independent power producers.

Shares of U.S. power, utility and natural gas companies sold off on Monday in some of the biggest recorded one-day drops, as new AI technology from Chinese start-up DeepSeek cast doubt on a projected surge in U.

Early Monday trading saw sharp declines across the US stock market, triggered by the unexpected rise of a Chinese AI app, DeepSeek. Over the weekend, DeepSeek soared to the top of Apple’s app chart, sending shockwaves through industries tied to artificial intelligence.