The numbers looked solid on the surface. Q4 revenue hit $18.02B, topping the $17.49B estimate, while adjusted EPS of $1.95 beat the $1.87 consensus. AI semiconductor revenue surged 74% year over year, and management guided Q1 revenue to $19.1B, well above the $18.27B Street estimate. Tan projected AI chip sales would double to $8.2B next quarter. But CFO Kirsten Spears flagged a problem that sent the stock lower.