Big Tech companies in the United States and Asia shed hundreds of billions of dollars in market value after Democrats swept the US midterm elections on campaigns calling for a slowdown in the rapid expansion of data centres and artificial intelligence.

The tech-heavy Nasdaq Composite closed more than 5.5% lower, wiping out an estimated $2.5tn in market value, according to Dow Jones data, and tipping the index into correction territory. The S&P 500 fell 4.4% and the Dow Jones Industrial Average dropped more than 3.4%, as the major US indexes suffered their worst day since 2025. Nvidia lost more than 9%, erasing over $400bn of its value, while the so-called Magnificent Seven tech giants together lost $1tn in a single trading session.

The sell-off spread to Asia on Friday morning. Japan's Nikkei 225 fell 6% in early trade, South Korea's Kospi sank more than 8.5%, triggering a circuit breaker to temporarily halt trading, and Taiwan's Taiex slid more than 8.3%.

Democrats won majorities in both the Senate and the House of Representatives, giving them control of Congress for the remainder of President Donald Trump's term. Mr Trump blamed his political opponents, saying the market had seen "one of the worst days in its history because of the election results". Democratic Senator Bernie Sanders called for an immediate freeze on data centre projects.

Susannah Streeter, chief investment strategist at Wealth Club, said fears that the vast sums poured into AI infrastructure may not deliver the returns investors had banked on were now colliding with the prospect of a sharp slowdown in data centre construction.