Stock market today: Dow, S&P 500, Nasdaq futures fall as Alphabet stock sells off, AI jitters return

US stock futures fell in premarket trading on Thursday as Alphabet's Q3 earnings sparked a sell-off in the stock and AI jitters returned to markets, dragging on the tech-heavy indexes.Futures on the Dow Jones Industrial Average (YM=F) fell 0.3%. Those on the S&P 500 (ES=F) slid 0.4%, while contracts for the Nasdaq-100 (NQ=F) fell 1.2%.Tech stocks snapped a positive run this week as investors digested the Fed's rate pause on Wednesday and earnings from Microsoft (MSFT) and Alphabet (GOOG, GOOGL). Microsoft beat analyst expectations on the top and bottom lines, while Alphabet sales came up short. Although Google posted cloud growth of 103%, concerns about its free cash flow and AI return on investment were the albatross on the company's quarter.A sell-off in AI names spread to Asian markets as South Korea's Kospi (^KS11) index declined. The iShares Semiconductor Index ETF (SOXX) also skidded after hours as Nvidia (NVDA), AMD (AMD), Micron (MU), and other chip stocks fell.Software stocks (IGV) also tumbled, with double-digit losses for Fortinet (FTNT) and ServiceNow (NOW) following their earnings reports.Markets will get another dose of hyperscaler earnings after the bell on Thursday when Amazon (AMZN) reports results. Several other stocks were moving in premarket trading on individual earnings: Eli Lilly (LLY), for example, popped 4% following strong Q3 results for its GLP-1 drugs.Thursday's market action comes after the Federal Reserve held rates unchanged on Wednesday afternoon. The decision had two dissenters who favored a rate hike amid sticky inflation. Meanwhile, European Central Bank President Christine Lagarde said on Thursday she will leave her post on Feb. 7, 2027, months ahead of schedule. The early departure comes at a delicate time for Europe, which continues to battle persistent inflation, surging bond yields, and domestic unrest in France over ballooning deficits and proposed austerity measures.