Asian stock markets tumbled on Friday as a technology-led sell-off on Wall Street spread to the region, with investors increasingly concerned that political shifts in the US could threaten the artificial intelligence investment boom. Japan's Nikkei index slumped 7 per cent shortly after the opening bell, while South Korea's Kospi and Taiwan's benchmark index fell more than 8 per cent. The declines subsequently eased as investors stepped in to buy shares at lower prices.