The existing literature on "two-sided markets" addresses participation externalities, but so far it has neglected pecuniary externalities between competing platforms. In this paper we build a model that incorporates both externalities. In our setup differentiated platforms compete in advertising...

This paper shows that the effects of employment protection critically depend on its enforcement. For this purpose, we capture evasion of employment protection via market exit in a setting of monopolistic competition. We find that the number of firms entering the market depends on firing costs...