AI Trade Unravels as Tech Stocks Post Worst Day Since 2020

Technology stocks suffered their worst session since 2020 as selling spread through the sector and into the artificial intelligence companies that had carried much of the market's recent rally. The S&P 500 lost an estimated $2.9 trillion in market capitalization over the day, the largest one-day loss of market value on record.

The scale of the move reflects how concentrated the index has become. A small group of large technology companies now makes up a big share of the S&P 500's total value, so when those shares fall together, the headline index drops far more than it would in a selloff limited to the rest of the market. The AI trade, which investors had bid up on expectations of heavy spending and fast revenue growth, was the main source of the pain.

For investors, the open question is whether this is a pause in a long run of gains or the start of a broader reassessment of AI valuations. Sharp drops like this tend to force out leveraged and momentum positions, and they put earnings and spending plans under closer scrutiny. Upcoming results from the largest chipmakers and cloud providers should show whether demand for AI infrastructure is holding up.