Rebounding tech stocks drove U.S. indexes higher a day after they tumbled on doubts about the artificial intelligence frenzy.

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 1.7% in afternoon trading and heading for its worst day in more than a month.

Wall Street is tumbling on fears the big U.S. companies that have feasted on the artificial-intelligence frenzy are under threat from a competitor in China.

Investors around the world are reassessing the prospects for technology companies after a Chinese artificial intelligence start-up rocked markets in the United States on Monday.

Silicon Valley venture capitalist Marc Andreessen has hailed DeepSeek as "one of the most amazing and impressive breakthroughs" in AI. The company says its latest AI models are on par with industry-leading models in the US - like ChatGPT - at a fraction of the cost.