Wall Street drops to its worst day since June after tech sell-off deepens

Worries are rising about whether hundreds of billions of dollars in AI investment will produce enough profit and productivity to be worth it.

The S&P 500 tumbled 1.8 per cent for its worst day since June, and it closed out a third straight losing week.

The US stock market remains only 3.1 per cent below its all-time high, which has boosted the value of workers’ 401(k) accounts.