DeepSeek topped the Apple App Store chart and sparked fears the Chinese company was quickly catching up with OpenAI's ChatGPT while costing far less.

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.

By Sinéad Carew, Amanda Cooper and Ankur Banerjee LONDON/SINGAPORE (Reuters) - Investors made a quick exit from a host of technology stocks from Tokyo to New York on Monday as the emergence of a low-cost Chinese artificial intelligence model challenged the dominance of current AI leaders such as Nvidia .