This chapter provides a concise summary and overview of the market failures approach to business ethics, one of the more influential (and controversial) general theories of business ethics to have emerged in the philosophical literature in recent decades. This view regards markets as a particular instance of a more general class of social institutions known as adversarial institutions. The central feature of adversarial institutions is that they achieve socially desirable outcomes indirectly, by setting up multiple agents in opposition to one another, in such a way that the competition that arises among them will promote the desired outcome. In order to function correctly, these institutions must provide actors with a set of permissions that provide specific exemptions from the constraints of everyday morality, in order to allow them to pursue the strategies that are required to generate the expected competition. But these permissions do not provide license to perform any action that advances their interests; they license only strategies that are consistent with the point of the institution. In the case of the market, this means that economic actors should refrain from taking advantage of institutional deficiencies likely to give rise to market failure. Law and regulation attempt to limit participants to such strategies, but in cases where legal rules are ineffective, there is a case for moral restraint on the part of participants.