S&P 500 Falls 1.2% in Its Worst Day Since July as Chip and AI Stocks Slide

The S&P 500 fell 1.2% on October 22, 2026, its worst day since July, as chip and artificial intelligence (AI) stocks led losses. The Nasdaq Composite tumbled 2.6%. Nvidia fell 4.4%; Lam Research dropped 11.8%. Most US stocks still rose. Brent crude oil climbed 4% to its highest level in five months, as traders weighed the war with Iran.