A sell-off in high-valuation technology shares deepened this week as doubts over the durability of the artificial-intelligence boom erased more than 3% from the Nasdaq 100 in just two sessions. Nvidia, the poster child of the AI rally, dropped 3.5% on Tuesday—its steepest one-day fall since April—during a trading frenzy that saw almost $33 billion of the chipmaker’s stock change hands. Palantir, Advanced Micro Devices and other AI beneficiaries also retreated after an MIT study suggested 95% of companies derive no financial benefit from generative-AI projects, echoing recent cautionary remarks by OpenAI chief Sam Altman. The broader market followed suit. The S&P 500 slipped for a fourth consecutive day on Wednesday, closing 0.27% lower at 6,394.05, while the Nasdaq Composite lost 0.65% to 21,176.51. Energy and defensive sectors helped the Dow Jones Industrial Average finish little changed, up 3.20 points at 44,925.47, but futures remained fragile as traders rotated out of this year’s best-performing names. Selling pressure spilled into Asia. SoftBank Group tumbled as much as 9.17% in Tokyo amid fresh scrutiny of its $2 billion stake in Intel, dragging the Nikkei 225 down roughly 1.8%. Semiconductor suppliers across South Korea, Taiwan and Hong Kong echoed the slide, and Europe’s Stoxx 600 technology sub-index also weakened, underscoring the global reach of the retreat. Market participants now look to a wave of U.S. retail earnings and to policy signals from the Federal Reserve. Minutes of the July FOMC meeting are due later Wednesday, and Chair Jerome Powell will deliver his final keynote address at the annual Jackson Hole symposium on Friday. Futures pricing shows investors still leaning toward a quarter-point rate cut in September, leaving Powell’s remarks—and any hint on the outlook for growth and AI investment—poised to set the tone for the next leg of trading.