Michael Katz

Multisided platforms are ubiquitous in today’s economy. Although newspapers demonstrate that the platform business model is scarcely new, recent economic analysis has explored more deeply the manner of its operation. Drawing upon these insights, we conclude that enforcers and courts should use a multiple-markets approach in which different groups of users on different sides of a platform belong in different product markets. This approach appropriately accounts for cross-market network effects without collapsing all of a platform’s users into a single product market.