The American Supreme Court decision in Ohio v. American Express (AMEX) will shape the future of US antitrust enforcement on multi-sided platforms. In a controversial landmark ruling, both the Court's majority and minority battled over definitions of relevant markets in the complex industry of...

Regulatory interventions aimed at promoting competition in digital markets face a challenge: how to design remedies that actually improve welfare? This Article helps provide an answer to this question. First, it maps out the frontier of remedy design: Part I.A summarizes antitrust and regulatory...