When corporations inflict injuries in the course of business, shareholders wielding environmental, social, and governance (“ESGâ€) principles can, and now sometimes do, intervene to correct the matter. In the emerging fact pattern, corporate social accountability expands out of its historic collectivized frame to become an internal subject matter—a corporate governance topic. As a result, shareholder accountability surfaces as a policy question for the first time. The Big Three index fund managers, BlackRock, Vanguard, and State Street, responded to the accountability question with ESG activism. In so doing, they defected against corporate legal theory’s central tenet, shareholder primacy. Shareholder primacy builds on a pair of norms. The first is substantive and concerns purpose— the firm should be managed for the shareholders’ financial benefit. The second norm is procedural and concerns power—shareholders should be able to tell managers how to run the firm. Once put into operation, the two norms are supposed to ensure that market control over production, and hence economic efficiency, is maximized. Prior to the Big Three’s turn to ESG activism, the two norms operated in tandem—power on the ground assured shareholder value maximization in the boardroom toward the generally accepted efficiency goal. But power on the ground now also triggers questions about shareholder accountability, and the Big Three, upon switching into activist mode to address those questions, put the two norms out of synch, causing the directive of management for the shareholders’ financial benefit to lose focus and compromising shareholder primacy in the performance of its mission. This Article looks closely at this confrontation between shareholder primacy and shareholder accountability, asking three questions: (1) whether investment institutions can legitimately sacrifice their investors’ financial returns in connection with the installation of socially responsible business practices at operating companies; (2) ...