Vertical Mergers: A Survey of Ex Post Evidence and Ex Ante Evaluation Methods

This article surveys recent empirical evidence on efficiencies and competitive harm that are associated with vertical mergers. It discusses both ex post or retrospective empirical studies that rely on post–merger data and ex ante or forecasting techniques that use premerger data. It develops the idea that although there is a need for vertical merger screening tools there are a number of problems that are associated with attempts to adapt horizontal screens to the vertical context. Mergers in the technology, media, and telecom sectors are emphasized because they tend to dominate contested vertical mergers.