Participants in a market, buyers and sellers, may need the service of an intermediary who will put them into contact and give them information about their potential trading partner. The intermediary chooses what price it will charge to each side to have access to its service. It also chooses...

We consider dynamic competition among platforms in a market with network externalities. A platform that dominated the market in the previous period becomes "focal" in the current period, in that agents play the equilibrium in which they adopt the focal platform whenever such equilibrium exists....