Alphabet, Google's parent company, suffered its largest single-day decline in history on October 29, with shares dropping 13% and erasing more than $500 billion in market value from the previous close. The plunge followed third-quarter earnings that fell short of Wall Street expectations despite strong revenue growth. Q3 revenue reached $127.58 billion, up 25% year-over-year but below the consensus estimate of $127.91 billion. Adjusted EPS came in at $2.67 versus the expected $2.97. While Google Cloud posted a standout 103% year-over-year increase to $30.71 billion, core advertising revenue underperformed, and free cash flow swung to a net outflow of $9.07 billion. Investors are increasingly concerned that surging AI infrastructure spending combined with slowing search advertising growth will continue to pressure Alphabet's profitability and cash flow.