Nigeria, Jan. 28 -- A broad selloff saw tech stocks sinking deep on Monday after DeepSeek sent shockwaves through Silicon Valley as the Chinese artificial-intelligence startup said it trained high-performing AI models cheaply.

DeepSeek, a one-year-old startup, presented a ChatGPT-like AI model called R1, which has all the abilities of other models. However, it is operating at a fraction of the cost of OpenAI's, Google's and Meta's popular AI models.

On Monday, DeepSeek's AI assistant rapidly overtook ChatGPT as the most popular free app in Apple's US and UK app stores, with attendant impact on the presumed dominance of the AI ecosystem by US companies.

US stocks dropped sharply by the close of business on Monday, with the tech-heavy Na...