Thursday's $3T tech sell-off, and what it means if you build AI products

On Thursday 5 November 2026 the Nasdaq Composite fell 5.52% to 24,315.00 and the Philadelphia Semiconductor Index about 11%, after midterm elections gave Democrats both chambers of Congress and voters in ten states rejected most local data-centre measures, which investors read as a cap on the US AI build-out. The selling hit a market already uneasy about AI capital spending outrunning cash flow, distressed-level credit at GPU cloud providers and 10-year Treasury yields near 5%, with more than $3 trillion of Nasdaq market value gone by midday on Fortune's count. The author, who runs product and engineering at an AI company, argues the market repriced the money and concrete behind the build-out while demand evidence did not move, citing AMD's above-expectation guidance and Anthropic's $17 billion third-quarter revenue.