Platform Competition and Interoperability: The Net Fee Model

We study the effects of competition and interoperabilty in platform markets. To do so, we adopt an approach of competition in net fees, which is well-suited to situations where users pay additional charges, after joining, for on-platform interactions. Compared to other approaches, net fees expand the tractable scope to allow platform asymmetry and variable total demand. Regarding competition, our findings raise concerns, including possible dominance-inducing entry, which symmetric models overlook. Our results are more optimistic towards the helpfulness of policies that promote interoperability among platforms, but they urge caution when total demand variability is a significant factor.