Market / Stocks

The AI selloff capped a bruising week for Wall Street

The Nasdaq fell 2.1 percent on Friday and about 4.5 percent on the week, its worst week since June, as investors started asking hard questions about who pays for the AI buildout. Chip stocks took the worst of it.

New York, United States · October 18, 2026

Friday finished the job the week had started. The S&P 500 fell 1.1 percent, the Nasdaq dropped 2.1 percent and the Dow Jones Industrial Average lost a comparatively mild 0.3 percent, according to the Associated Press market summary. Across the week the Nasdaq fell about 4.5 percent and the S&P 500 about 1.9 percent, while the Dow actually rose 0.7 percent. For both the S&P 500 and the Nasdaq it was the worst week since June.

The selling was concentrated exactly where the optimism had been. Micron fell 5.6 percent on Friday, AMD dropped 6 percent, Broadcom lost 4.5 percent and Intel slid 5.8 percent. The platform giants were not spared either: Meta fell 3.7 percent and Alphabet 2.5 percent. When the Dow rises in the same week the Nasdaq posts its worst result in months, that is not a market falling out of bed. It is money rotating, out of the trade everyone was crowded into and into defensives that had been left behind.

The worry driving it is specific, and it is worth naming precisely. Investors are not suddenly doubting that AI gets used. They are doubting the financing behind the buildout: the borrowing costs, the debt being taken on to fund data centres, and names like CoreWeave, whose debt concerns Reuters flagged as tech stocks wobbled again this week. A boom funded with cheap confidence behaves very differently once lenders start asking for their return first.

That makes the coming week a genuine test rather than a pause. Reuters' Week Ahead has Meta kicking off the hyperscaler earnings season, and those results will be read less for revenue than for spending plans and how they are funded. If the biggest buyers of AI hardware can show the outlay earning its keep, the selloff looks like a reset in an expensive trade. If they cannot, Friday's numbers will look less like a bad week and more like a change of mind.