Microsoft jumped over 15 per cent, boosting its stock market value by US$450 billion, the greatest-ever single-day increase for a company on Wall Street. This year, investors have been spooked by heavy spending on AI at big technology firms. Negative cash-flow reports from Alphabet and Tesla last week sparked a bout of selling in AI-linked stocks, with chip stocks also under pressure as investors questioned high valuations. The economy grew at a 1.5 per cent rate, slower than estimates of 2.1 per cent growth, data showed. Across the US stock market, advancing stocks outnumbered falling ones by a 2.2-to-one ratio.