Proxy advisors play an important role by providing investors with research and recommendations on how to vote their shares. This paper examines how proxy advisors affect the quality of corporate decision-making. We analyze a model in which a monopolistic advisor o¤ers to sell information to shareholders, who decide whether to acquire private information and/or buy the advisors recommendation, and how to cast their votes. We show that the proxy advisors presence can decrease the quality of decision-making, even if its information is more precise than each shareholders information and no party has a conict of interest. This is because there is a wedge between privately optimal and socially optimal information acquisition decisions, leading to ine¢ cient crowding out of private information production. We also evaluate several existing proposals on regulating proxy advisors and show that some frequently suggested policies, such as promoting competition in the proxy advisory industry, can have a negative e¤ect.