Immediately following an initial public offering, underwriters often repurchase shares of poorly performing offerings in an apparent attempt to stabilize the price. Using proprietary Nasdaq data, I study the price effects and determinants of price support. Some of the key findings are (1) Stabilization is substantial, inducing price rigidity at and below the offer price; (2) I find no evidence that stocks with larger information asymmetries are stabilized more strongly; (3) Larger underwriters stabilize more, perhaps to protect their reputations with investors; and (4) Investment banks with retail brokerage operations stabilize much more than other banks, inconsistent with the view that stabilization benefits primarily institutional investors.