NEW YORK (AP) — Wall Street’s superstars are tumbling Monday as a competitor from China threatens to upend the artificial-intelligence frenzy they've been feasting on.

The S&P 500 was down 1.9 per cent in late trading and heading for its worst day in more than a month. Big Tech stocks took some of the heaviest losses, with Nvidia down 18 per cent, and they dragged the Nasdaq composite down 3.7 per cent. 

The damage was centered on AI-related stocks, while the rest of the market held up much better. The Dow Jones Industrial Average was up 243 points, or 0.5 per cent, with roughly an hour remaining in trading, and the majority of U.S. stocks were rising. But anyone holding an S&P 500 index fund, as many savers do in their 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. DeepSeek had already hit the top of the chart for free apps on Apple’s App Store by Monday morning, and analysts said such a feat would be particularly impressive given how the U.S. government has restricted Chinese access to top AI chips.

Skepticism, though, remains about how much DeepSeek’s announcement will ultimately shake the economy that's built around the AI industry, from the chip makers making semiconductors to the utilities hoping to electrify vast data centers gobbling up computing power. 

“It remains to be seen if DeepSeek found a way to work around these chip restrictions rules and what chips they ultimately used as there will be many skeptics around this issue given the information is coming from China,” according to Dan Ives, an analyst with Wedbush Securities.

DeepSeek’s disruption nevertheless rocked AI-related stocks worldwide.

In Amsterdam, Dutch chipmaking equipment company ASML slid 7 per cent. In Tokyo, Japan’s Softbank Group Corp. lost 8.3 per cent to pull closer to where it was before leaping on an announcement trumpeted by the White House  that it was joining a partnership to invest up to $500 billion in AI infrastructure. 

And on Wall Street, shares of Constellation Energy lost more than a fifth of its value, 22 per cent. 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 4.53 per cent from 4.62 per cent late Friday.

It’s a sharp turnaround for the AI winners, which had soared in recent years on hopes that all the investment pouring in would remake the global economy and deliver gargantuan profits along the way. Such stellar performances also raised criticism that their stock prices had gone too far, too fast. 

Before Monday's drop, which was on track to be 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, for example. 

It was just on Friday that Meta Platforms CEO Mark Zuckerberg was saying he expects his company to invest up to $65 billion this year and grow its AI teams significantly, while talking up a datacenter in Louisiana that will be so large it could cover a significant part of Manhattan. 

A small group of such companies has become so dominant that they’ve come to be known as the “Magnificent Seven.” These companies — Alphabet, Amazon, Apple, Meta Platforms, Microsoft, Nvidia and Tesla — alone accounted for more than half the S&P 500’s total return last year, according to S&P Dow Jones Indices.

Their immense sizes give them huge sway over the S&P 500 and other indexes that give more weight to bigger companies. That's why many 401(k) holders felt the pain of Nvidia's drop, so long as they owned a fund that tracks the S&P 500, even if they didn't know they owned any Nvidia. 

It also shows the risk of betting too much on just a few winning stocks, something that market experts call “concentration risk.” That “can feel good when those few names or ideas are on the ascent, but it is even more dangerous when disruptions take place,” said Brian Jacobsen, chief economist at Annex Wealth Management.

Still, he suggested not overreacting to Monday’s sharp swings. “It is possible that the news out of China could be overstated and then we could see a reversal of the recent market moves,” Jacobsen said. “It is also possible that the news is true, but then that would present new investment opportunities.”

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.

The pressure is on companies to keep delivering strong profits, particularly after a recent jump in Treasury yields, even with Monday's decline. When bonds are paying more in interest, they put downward pressure on stock prices. 

So far, big U.S. companies have been reporting better results than analysts expected. AT&T became the latest on Monday, and its stock rose 6.8 per cent. 

In stock markets abroad, movements for broad indexes across Europe and Asia weren’t as forceful as for the big U.S. tech stocks. France’s CAC 40 fell 0.3 per cent, and Germany’s DAX lost 0.5 per cent.

In Asia, stocks edged 0.1 per cent lower in Shanghai after a survey of manufacturers  showed export orders in China dropping to a five-month low. 

The Federal Reserve holds its latest policy meeting later this week. Traders don’t expect recent weak data to push the Fed to cut its main interest rate. They’re virtually certain the central bank will hold steady, according to data from CME Group. 

———

AP Business Writers Matt Ott and Elaine Kurtenbach contributed. 

– Stan Choe, The Associated Press