China's DeepSeek sends US tech shares tumbling

Shares of the largest US technology companies fell sharply after Chinese start-up DeepSeek unveiled R1, an artificial intelligence model comparable in capability to the best American systems.

Particular attention was drawn by the company's claims that training the model cost several times less than its competitors'. The DeepSeek app topped the free app rankings on the US App Store.

Nvidia's market capitalisation fell by almost 600 billion dollars in a single trading day, a record drop for one company in the history of the US stock market.

President Donald Trump called DeepSeek's emergence a "wake-up call" for American industry. Experts say investors are reassessing expectations for spending on AI infrastructure.