A new A.I. model, released by a scrappy Chinese upstart, has rocked Silicon Valley and upended several fundamental assumptions about A.I. progress.

The Chinese artificial intelligence app DeepSeek became the most downloaded free app in the U.S. on Apple’s app store and its low cost claims are putting the pressure on major American tech companies.

Liang Wenfeng, the 40-year-old founder of DeepSeek, trained as an engineer and then launched a hedge fund. Now he’s enjoying sudden success with his AI chatbot.