We study the gains from trade in a model with oligopolistic competition, heterogeneous firms and innovation, and provide a formula to decompose the mechanism. The new insight we provide is that market concentration can be a welfare-relevant feature of market power above and beyond markup...

We characterize a monopolist's optimal offer of service plans when only informed customers know already at the contracting stage whether their demand is high or low, while uninformed customers may learn their demand only after incurring some costs, if at all. While informed customers purchase...