The Nasdaq & S&P 500 fell after Chinese startup DeepSeek shows AI can be built cheaply, sparking fears AI spending will stall. The blue-chip Dow rose.

The S&P 500 and the Nasdaq hit over one-week lows on Monday, as the surging popularity of a low-cost Chinese artificial intelligence model knocked shares of chipmaker Nvidia and other companies benefiting from investments into the technology.

American AI stocks got sucker punched after China's DeepSeek app reportedly showed advancements against rivals sending investors into sell mode, shaving 3% off the Nasdaq.