Digital platforms frequently refer their users to competitors. We show that these references induce a business-sharing effect that may relax competition for users, resulting in lower quality of content. More surprisingly, user surplus may also decrease as the quality effect may overwhelm the...

This article provides an overview of the competitive issues surrounding online platforms. The general theme is that while much has been made of the structural features of online platforms there is little hard evidence that these are durable monopolies. Nonetheless, there are concerns about the...