Google suffered its worst single-day selloff in history, with shares plunging more than 11% and roughly $500 billion in market value wiped out. A death cross formed during intraday trading, dragging down tech stocks and the Nasdaq. The latest earnings report showed that several core business metrics fell short of market expectations: AI spending devoured cash flow, share buybacks dropped to zero, and pricing in the core search business came under pressure. The event triggered a reassessment of the investment case for AI, with the market shifting from rewarding tech companies for growth in AI capital expenditure to demanding evidence of returns. The earnings report laid bare a core contradiction: Google's search query volume hit a five-year high, yet search revenue growth fell sharply, and the lower monetization rate of AI Mode fueled concerns that search monetization is being eroded. YouTube revenue growth also fell below the threshold investors were watching. The lone bright spot was Google Cloud, whose performance beat expectations—though related profits were largely consumed by heavy AI R&D spending. At the same time, the company's free cash flow consumption far exceeded expectations, and its financing structure underwent a fundamental shift: share buybacks fell to zero, replaced by large-scale fundraising through share issuance and debt offerings. The fallout spread across the entire AI sector, and market rotation trends emerged. Multiple institutions lowered their price targets for Alphabet, further underscoring the logic of differentiation among winners in the AI infrastructure investment space.