A brutal sell-off swept Wall Street Thursday, led by stocks tied to the buildout of AI data centres, with the S&P 500 falling 4.4 per cent for its worst day since U.S. President Donald Trump shook markets worldwide in April 2025 with his "Liberation Day" tariffs. The Dow Jones Industrial Average sank 1,833 points, or 3.4 per cent, while the Nasdaq Composite tumbled 5.5 per cent and sank 11.9 per cent below its all-time high set last month. Canada's main stock index lost 736.13 points at 35,605.27, weighed down by losses in the technology sector, and the Canadian dollar traded for 71.48 cents US compared with 71.63 cents US on Wednesday. Stock markets around the world felt pressure, and South Korea's Kospi index tumbled 5.3 per cent. Stocks have been swinging for months on worries that construction of further AI data centres may slow because of how expensive it's become to borrow money, and critics said AI stock prices had shot too high and were in a bubble. Tuesday's U.S. midterm elections added another challenge, as nationwide victories for Democrats raised the possibility that governments could force pauses in construction of more data centres. Nvidia fell 9.3 per cent and was by far the heaviest weight on the S&P 500, while Advanced Micro Devices tumbled 17.3 per cent