We study an information sale problem in which a monopolist proxy advisor sells recommendations to a firm’s shareholders for corporate voting. We find that even an unconflicted proxy advisor skews its recommendations based on its clients’ beliefs or preferences. A novel bias-quantity relationship affects firm value. Under some parameters, shareholders’ biased beliefs or preferences can lead shareholders to make more information purchases, which enhances their collective decision-making. Thus, firm value may increase despite the negative effects of biased proxy voting recommendations. JEL D82, G34, L15 Received: April 16, 2019; editorial decision March 25, 2020 by Editor Uday Rajan.