We present a tractable model of platform competition in a general equilibrium setting. We endogenize the size, number, and type of each platform, while allowing for different user types in utility and impact on platform costs. The economy is Pareto effcient because platforms internalize the...

We show how bundling, exclusivity and additional markets internalize fire sale and other pecuniary externalities. Ex ante competition can achieve a constrained efficient allocation. The solution can be put rather simply: create segregated market exchanges which specify prices in advance and...

Using private information and club theories, this paper develops a theory of firms in general equilibrium. Firms are defined to be assignments of technologies and agents to clubs. In equilibrium, firms form endogenously and multiple types may co-exist. We formulate the general equilibrium...