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AI-focused stocks trigger record one-day $2.9 trillion loss on US markets

A broad sell-off on US exchanges on Thursday, led by steep losses in AI-related stocks, erased about $2.9 trillion from the combined market value of S&P 500 companies—the largest one-day drop on record.

AI-focused stocks trigger record one-day $2.9 trillion loss on US markets

AI Newsroom · 6 November 2026 · 2 min read

A broad selling wave hit US exchanges on Thursday, with sharp declines in AI-related stocks driving a record one-day loss in market value. According to MarketWatch, the combined market capitalization of S&P 500 companies fell by approximately $2.9 trillion in a single session—the largest daily drop on record.

Index moves

  • The S&P 500 fell 4.4%.
  • The Nasdaq declined 5.5%.
  • Companies in the Nasdaq Composite lost about $2.5 trillion in market value during the day.
  • Both major benchmarks recorded their worst closing day since the tariff-war shock in April 2025.

Semiconductors and tech hardest hit

The Philadelphia Semiconductor Index plummeted 12.3%, the biggest one-day drop since March 2020. The S&P 500 technology sector index lost 7.3% of its value.

Notable individual moves during the day:

  • Nvidia: -9.3%
  • AMD: -17.3%
  • Micron: nearly -17.5%
  • Sandisk: -22%

Drivers of the sell-off

Market participants pointed to growing doubts about the future of AI investment as the main cause of the liquidation. Two key concerns were highlighted:

  1. Political and regulatory risk: following a Democratic midterm victory, investors feared potential tightening of rules around data-center construction and operation, which could curb development of AI-related infrastructure.
  2. Returns and speculative positioning: questions about the economic payback from AI investments and the unwinding of sizable speculative positions in the sector exacerbated the downturn.

Volatility and market implications

The scale of the panic was reflected in a near 70% single-day rise in the VIX, the so-called Wall Street fear index—its largest daily jump in two years. The Nasdaq fell to roughly 12% below its early-October all-time high, officially entering correction territory.

Why this matters

A record one-day market-value loss underscores a rapid re-pricing of growth expectations for AI-related companies. If regulatory uncertainty and doubts about investment returns persist, vulnerable stocks and related infrastructure projects could face prolonged pressure.

This article does not constitute investment advice or a recommendation.

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