We model an IPO company's optimal response to the presence of sentiment investors. "Regular" investors are allocated stock that they subsequently sell to sentiment investors. Because sentiment demand may disappear prematurely, carrying IPO stock in inventory is risky, so for regulars to break even the stock must be underpriced. The issuer still gains as the offer price capitalizes part of the regulars' expected trading gain. This resolves the empirical puzzle that issuers do not appear to price their stock aggressively in hot markets. The model generates new refutable predictions regarding the extent of long-run underperformance, offer size, flipping, and lockups.