US stock indices on Wednesday recorded their worst day in more than 18 months after lacklustre overnight results from index heavyweights Tesla and Alphabet deepened a technology sector sell-off.

The blue-chip S&P 500 fell 2.3 per cent, its worst day since December 2022, while the tech-heavy Nasdaq Composite fell 3.6 per cent, its worst day since October 2022. The losses in both were driven by big tech stocks, including Nvidia, Microsoft, Apple and Tesla. Tech — and artificial intelligence stocks in particular — have driven the bulk of market gains this year.

Tesla fell 12.3 per cent, its worst daily performance since 2020, after the electric-car maker on Tuesday announced profits well short of expectations. Google parent Alphabet fell 5 per cent, its worst day since January, despite narrowly beating analysts’ revenue forecasts. Advertising revenue from YouTube missed consensus estimates.