US stocks weekly: Shaky

** S&P 500 .SPX declines second straight week, falls 0.5% in rocky trading as risk-off sentiment pervades .N

** Dow .DJI rises 0.4%, tech-heavy Nasdaq Composite .IXIC loses 0.7%

** With weakness, a Nasdaq breadth measure nears prior washout lows. Indeed, the Composite is not that far from its highs, but its internals have been telling a different story

** This as the S&P 500 stalls near records, putting key levels in focus, and Nasdaq's five-month stall leaves support in the spotlight

** US 10-Year Treasury yield plummets below 5%, on track to end around that level as fears about AI boom sustainability flare, boosting safe-haven appeal of government debt US/

** In the end, a minority of sectors teeter: Just Communication Services, Industrials and Technology wobble, while defensive names and Energy stand steady

** Communication Services .SPLRCL plunges 6.2%. Netflix NFLX.O stumbles on weak Q4 profit guidance, lowered 2026 advertising rev forecast

Facebook owner Meta META.O falls after announcing new class of stock to fund its costly AI plans, while CEO Mark Zuckerberg maintains control of firm

** Industrials .SPLRCI crumble 1.9%. HVAC contractor Comfort Systems USA FIX.N drops as worries grow over durability of the data-center buildout

Bloom Energy BE.N tumbles despite fuel cell maker's earnings beat, trimming stock's YTD gain to ~122%

** Tech .SPLRCT ticks down 0.3%. Server maker Super Micro SMCI.O jumps after upbeat qtrly forecast on robust AI demand, helping lift chip-related names on Weds

Though, on Thurs, chip stocks retreat as AI optimism fades

Semiconductor index .SOX falters 3.2%

** Consumer Staples .SPLRCS up 0.5%. Procter & Gamble PG.N leaps after qtrly results beat as consumer demand holds up

** Consumer Discretionary .SPLRCD up 0.5%. Tesla TSLA.O rises on Weds after Musk floats SpaceX merger SPCX.O, then skids on Thurs after EV maker cuts 2026 capex forecast. Still, TSLA notches ~5% weekly advance

** Financials .SPSY up 0.7%. Blackstone BX.N climbs after Q3 profit beat, and upbeat tone on monetization activity in Q4 sparks rally in alternative asset manager peers

Card giant American Express AXP.N falls on Fri after announcing Q3 results, plans to cut 5% of workforce; CEO says co needed to become more "agile and efficient"

** Healthcare .SPXHC ascends 1.5%. However, Moderna MRNA.O extends slide as analysts question valuation after co and partner Merck MRK.N publish cancer vaccine data, following leak of the results on an oncology website

** Energy .SPNY adds 1.5%. Group rises as oil prices surge on Saudi attack fears

Oilfield services provider SLB SLB.N pops after profit beat, signals recovery in Middle East following conflict-related disruptions

** Meanwhile, AAII pessimism climbs as investors turn more cautious

** SPX performance YTD:

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