Stock Market Today, Nov. 5: Nasdaq Suffers Worst Day in 18 Months as AI Trade Comes Under Fire

The Nasdaq dropped 5.52% to enter correction territory, with the S&P 500 falling 4.33% in its worst session since early 2025. The sell-off was driven by a reassessment of AI investment returns and midterm election-driven regulatory concerns, hitting semiconductor stocks particularly hard. Investors are questioning whether billions in AI data center spending will generate sufficient returns to justify valuations.