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.

DeepSeek released an open-source artificial intelligence model in December, saying it took only two months and less than $6 million to create it.

The S&P 500 and the Nasdaq dropped 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.