Antitrust agencies around the world are increasingly focusing on digital indus- tries. Critics have justifiably questioned the ability of competition agencies to make beneficial enforcement decisions given the complexity and rapid pace of change in online markets. This Article discusses those criticisms and addresses the argument that, because the error costs of overenforcement of antitrust laws in digital markets would be much higher than the error costs of underenforcement, courts and antitrust agencies should presume against antitrust intervention in digital industries. While acknowledging that there is often good reason for such modesty in enforcement, this Article discusses several ways in which competition policy can adjust to better account for potential costs and benefits of enforcement in digital platform markets. It argues that nonprice effects related to information and innovation are particularly important to the performance of online platforms, and may hold the key to a better understanding of the costs of antitrust underenforcement and the assessment of the competitive effects of conduct and transactions in digital industries.