Abstract
Acquisitions can shift the market structure of a digital platform in a way that affects subsequent market entries and hence the platform’s base of complementors. Synergies that complementor acquirers accrue can be entry-deterring. We develop a two-by-two typology of acquisition synergies in a multisided platform based on sides (user side or complementary-technology side) and economies (scale or scope). We then leverage over 279 thousand app developers’ entry decisions into product categories in Apple’s iOS App Store, over 71 million customer reviews, and over 12 thousand unique software development kits to construct measures of synergies. Our paper contributes to the platform literature by demonstrating the entry-deterring effects of synergies that complementor acquirers can exploit.