Wall Street’s superstars are tumbling Monday as a competitor from China threatens to upend the artificial-intelligence frenzy that’s created a spending bonanza. The S&P 500 was down 1.7% in midday trading and heading for its worst day in more than a month.

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.

According to a paper authored by the lab, the DeepSeek-R1 model outperforms cutting-edge models such as OpenAI’s o1 and Meta’s Llama AI models across multiple benchmarks.