Shares in major chip firms have fallen sharply in the US and Asia as a sell-off in artificial intelligence-related stocks deepened. Trading on South Korea's benchmark Kospi index was paused temporarily on Tuesday morning after sliding by 8%. It fell further after the 20-minute halt was lifted to trade around 10% lower.

The slump was led by technology firms, with Samsung Electronics and SK Hynix both falling by about 12%. The tech-heavy Kospi has been halted eight times so far this year under a stock market mechanism known as a circuit breaker, which is designed to calm panic selling. The index had more than doubled from the start of the year to mid-June but has since lost around a third of its value.

In recent months, stock market trading has been particularly volatile in South Korea as it has attracted large numbers of retail investors. On Monday, US-listed shares in SK Hynix fell by 7.5% to well below the $149 (£112.11) offer price when it made a record-breaking debut on the Nasdaq on 9 July.

Japan's Nikkei 225, which is also dominated by tech companies, was almost 3.8% lower on Tuesday morning. Nvidia shares fell on Monday after the Wall Street Journal reported that it is in talks to provide around $250bn for OpenAI as part of a massive data-centre project.

The decline allowed Apple to overtake Nvidia as the world's most valuable company after the iPhone maker rose by about 25% this year. As governments and companies spend hundreds of billions of dollars on developing AI capabilities, some analysts have questioned whether the technology can become profitable enough to recoup such huge investments.