What is DeepSeek, the Chinese AI company upending the stock market?

A frenzy over an artificial intelligence chatbot made by Chinese tech startup DeepSeek was upending stock markets Monday and fueling debates over the economic and geopolitical competition between the U.S. and China in developing AI technology.

DeepSeek’s AI assistant became the No. 1 downloaded free app on Apple’s iPhone store Monday, propelled by curiosity about the ChatGPT competitor. Part of what’s worrying some U.S. tech industry…