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....

We study monopoly and duopoly pricing in a two-sided market with dispersed information about users' preferences. We first show how the dispersion of information introduces idiosyncratic uncertainty about participation rates and how the latter shapes the elasticity of the demands and thereby the...