The separation of ownership and control for public firms may lead to fully dispersed ownership where no shareholder has an incentive to engage in governance. This column argues that blockholders (owners of large stakes) play a critical role in long-term governance, partly through a credible threat to sell their stakes. This threat is undermined by well-intentioned policy moves to create holding-period incentives and requirements. If they succeed, these policies will make exit less likely and blockholders will lose a method to discipline managers.