We model the trade-offs of an investor who builds positions and exerts governance in competing firms. The implicit cost of doing traditional governance is under-diversification, since her incentives to cut slack and improve efficiency are low when she has similar exposure to all firms in an industry. The benefit is to escape the incentive to push firms to compete less aggressively, and avoid the potential litigation and reputational costs. We study how these trade-offs shape the equilibrium interactions of ownership, governance, and competition, and the role of competition policy in a world where investors influence the objectives of competing firms.