We derive a New Keynesian Phillips Curve under Calvo staggered pricing and price competition. Firms strategic interactions induce price adjusters to change their prices less when there are more firms that do not adjust. This reduces the slope of the Phillips curve and generates an additional...

We study platforms competing in commissions on revenues of sellers engaged in monopolistic competition, as the app providers on the app stores of iPhones and Android devices. Free entry of sellers on each platform generates multihoming superstars and a long tail of singlehoming sellers....