Wall Street’s superstars tumbled Monday as a competitor from China threatens to upend the artificial-intelligence frenzy they’ve been feasting on.

The S&P 500 dropped 1.5%, dragged down in large part by a 16.9% fall for Nvidia. Other Big Tech stocks also took heavy losses, and they pulled the Nasdaq composite down 3.1% for its worst loss in more than a month.

The damage was focused on AI-related stocks, while the rest of the market held up much better. The Dow Jones industrial average rose 289 points, or 0.7%, and the majority of U.S. stocks climbed. But anyone holding an S&P 500 index fund, which are found in many 401(k) accounts, felt the pain because of how influential those tech giants have become on indexes.

The shock to financial markets came from China, where a company called DeepSeek unveiled a large language model that can compete with U.S. giants but at potentially a fraction of the cost.

In Amsterdam, Dutch chipmaking equipment company ASML slid 7%. In Tokyo, Japan’s Softbank Group Corp. lost 8.3%.

And on Wall Street, Constellation Energy lost more than a fifth of its value, 20.8%. The company has said it would restart the shuttered Three Mile Island nuclear power plant to supply power for data centers for Microsoft.

All the worries sent investors toward bonds, which can be safer investments than any stock. The rush pushed the yield of the 10-year Treasury down to 4.52% from 4.62% late Friday.

Before Monday’s drop, which was its worst since the 2020 COVID crash, Nvidia’s stock had soared from less than $20 to more than $140 in less than two years.

All told, the S&P 500 fell 88.96 points to 6,012.28. The Nasdaq composite dropped 612.47 to 19,341.83, and the Dow Jones Industrial Average rose 289.33 to 44,713.58.

More big swings may be ahead. Apple, Meta Platforms, Microsoft and Tesla are all on the schedule this upcoming week to report how much profit they made at the end of 2024.

— Associated Press