US stocks weekly: Short-circuit

S&P 500 .SPX drops 1.9% in wild trading as jitters over lofty tech valuations and ambitious AI-spending plans resurface .N

Dow .DJI loses 1.9%, while tech-heavy Nasdaq Composite .IXIC tumbles 2.7%

SPX ends longest stretch of closes above its 50-day moving average since 2007 on Mon; then breaks its 100-DMA on Thurs, as traders eye bitcoin BTC=, more technical damage

Indeed, when animal spirits slump, stocks struggle

CBOE Volatility Index .VIX, Wall Street's "fear gauge", spikes to close at highest since late Apr before receding to roughly 23.40

U.S. 10-Year Treasury yield US10YT=RR on course for weekly decline to around 4.07% as rate-cut bets rise US/

Most sectors fried: Technology biggest burn out, while Healthcare and Communication Services most resilient

Tech .SPLRCT dives 4.7%. Nvidia NVDA.O initially jumps on Thurs after stellar results, forecast, but then sputters and drags down chip stocks

Semiconductor index .SOX slides ~6%

Cloud firm Oracle ORCL.N extends its selloff on worries about AI

Consumer Discretionary .SPLRCD retreats 3.3%. Home Depot HD.N sags after annual profit forecast cut, hurt by slowdown in big-ticket renovations and do-it-yourself projects

Consumer Staples .SPLRCS up 0.8%. Walmart WMT.N rises after bumping up annual forecasts heading into the holiday season

Though Target TGT.N falls after bigger-than-expected drop in Q3 comparable sales as U.S. consumers pull back on discretionary spending on apparel, home decor

Healthcare .SPXHC climbs 1.8%. Eli Lilly LLY.N hits record, becomes 1st drugmaker to hit $1 trln market value on weight-loss demand

Communication Services .SPLRCL surges 3%. Google parent Alphabet GOOGL.O leaps after Berkshire Hathaway BRKa.N reveals new stake worth about $5 bln, adds to gains following positive views on its latest Gemini 3 AI model

Meanwhile, individual investors fret over market concentration in Big Tech

SPX performance YTD: