• The seven most-valuable U.S. tech companies lost a combined $1 trillion in market value at the start of trading on Monday.
• The tech-heavy Nasdaq was down more than 3% following the index's steepest three-week slide in two years.
• Nvidia fell about 6% and Apple was down more than 4%.

As U.S. markets opened for trading on Monday, tech's megacap companies lost about $1 trillion in market cap, deepening a downturn that sent the Nasdaq into correction territory last week.

Nvidia shed more than $300 billion in market cap at the opening bell, though it quickly recovered about half of its loss. Shares of the chipmaker closed down 6.4% for a loss of $168 billion. Apple and Amazon's valuation plummeted $224 billion and $109 billion, respectively, at the market open. Apple ended down 4.8%, or $162 billion in market cap. Amazon dropped 4.1% at the close, or $72 billion.

Add all that to steep declines in Meta, Microsoft, Alphabet and Tesla, and the seven most-valuable tech companies lost $995 billion in the early moments of trading. They bounced back some as trading progressed.

Markets fell broadly on Monday as concerns about a recession stemming from disappointing economic data last week pushed Japan's Nikkei 225 down 12% on Monday, its worst day since the 1987 "Black Monday" crash on Wall Street. Bitcoin plummeted 11%, leading a sell-off in cryptocurrency and related stocks.

Within technology, investors have been getting nervous for weeks. The Nasdaq slumped 3.4% last week, wrapping up its worst three-week stretch in two years, before losing another 3.4% on Monday. Amazon, Alphabet and Microsoft all gave Wall Street reasons for concern in their reports, contributing to a slide among their peers.

It is a sharp change from a few months ago, when investors cheered as Meta CEO Mark Zuckerberg and Google CEO Sundar Pichai both said their companies were spending heavily to build out their artificial intelligence infrastructure.

Nvidia, a company unknown to most Americans, was the biggest beneficiary due to its graphics processing units, or GPUs, powering the AI boom. The company surpassed $3 trillion in market cap and briefly passed Microsoft and Apple to become the world's most valuable company. Its market cap now sits below $2.5 trillion.

Some analysts have been sounding the alarm of late regarding a potential overinvestment in AI.

A widely read Goldman Sachs note from June warned that the biggest-spending companies had little to show for their AI expenditures. Elliott Management, one of the largest hedge funds in the world, reportedly told clients that Nvidia was in a "bubble" and the AI frenzy was "overhyped."

Nvidia reports earnings later this month. The company has generated revenue growth in excess of 200% for the past three quarters.

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