Wall Street's AI rally faces its biggest test yet

US stocks suffered their sharpest sell-off in years on Thursday, with the tech-heavy Nasdaq falling 5.5 percent, as investors questioned whether the decline signals a larger crash or a temporary setback. The rout hit major tech firms like Nvidia, which lost 9 percent in a day, and spread globally, with South Korea's Kospi dropping 6 percent and European indexes falling over 1 percent. Friday brought partial recovery, with the S&P 500 up 0.7 percent at open. The sell-off followed Democratic election wins and concerns about data centre restrictions, though analysts debate whether the long bull run, driven heavily by AI stocks, is sustainable. Nvidia's upcoming quarterly results in 11 days are now seen as critical.