US stocks suffer broad sell-off, Nasdaq falls nearly 4%

U.S. equities sold off broadly on November 6, with the Nasdaq Composite falling about 4% and the Nasdaq 100 dropping 4.52%, while the S&P 500 lost 2.7% and broke below both its 100-day moving average and September lows; the Nasdaq gauges each closed under their 200-day moving averages. The AI complex led the decline, with losses spreading from chips and memory to data-center networking, optical communications, AI cloud and power suppliers, and SanDisk, Western Digital, Micron, SK Hynix, AMD, Qualcomm, Arm, Lam Research, Applied Materials, Nebius, CoreWeave and Bloom Energy all falling more than 10%, with Bloom Energy and SanDisk down nearly 18%. Market breadth deteriorated sharply, with decliners outnumbering advancers nearly 4-to-1 on the Nasdaq, about 2.5-to-1 on the NYSE and roughly 1.6-to-1 in the S&P 500, showing the selling has widened beyond mega-cap technology. The move matters because it marks a broad unwind of AI-linked positioning rather than an isolated tech pullback, and the breach of key moving averages signals momentum damage across major indexes. Investors will watch whether the 200-day line holds on a closing basis and whether selling pressure in AI infrastructure names broadens further into the wider market.