A slew of stocks, including chip maker Nvidia, fell Monday after Chinese startup DeepSeek released an AI model that runs on less-advanced chips and at a lower cost than U.S. rivals.

In a matter of days, DeepSeek proved to be so popular as to climb to the top of Apple's App Store, surpassing OpenAI's ChatGPT as the most downloaded app. But for owners of Nvidia stock, and stock traders in general, DeepSeek is on track of becoming a black swan — an unexpected event with extreme consequences.