US stocks took a beating on Friday, October 30, with losses that started at the open and deepened through the day. The S&P 500 closed down 1.82% at 7,580.07, its worst day since June and its third straight losing week, which wiped out the index's gain for October even though it hit a record high earlier in the month. The tech-heavy Nasdaq sank 2.86% to 25,437.00, and the Dow Jones Industrial Average dropped about 572 points, or 1.1%. Intel led the carnage, plunging about 29% for its worst day since 1974 after giving a profit forecast below analysts' expectations, which erased roughly $140 billion of its market value.

The selloff was driven by fresh worries that the AI frenzy has pushed prices too high. Investors were already rattled by Alphabet, which had its worst day on record on Thursday after telling investors it burned through more cash over the summer than in the spring, and Amazon's earnings and outlook added to the unease on Friday. The big question hanging over the market is whether the huge spending on AI infrastructure will pay off, and when. Not everything is collapsing, though, because the S&P 500 is still up about 11% this year, and Intel's drop was far deeper than any of its peers'. One bad day doesn't tell us where stocks are headed, but it does show how much of the market's confidence rests on the AI story.