I study a merger between producers of complement inputs facing entry of superior inputs, with investment by the incumbents in deterministic cost reduction and by the entrants in probabilistic innovation, and competition in prices. The merger is profitable by solving Cournot complementarity...

One of the pioneering works on endogenous market structures, by Tandon (1984), has extended the standard Cournot model with linear demand to endogenous entry and sunk R&D costs to show that the endogenous number of firms is independent from the size of the market. I generalize the model in many...

I analyze the role of leadership in multi-sided markets as online advertising. Search and display advertising are better characterized by (respectively) quantity and price competition. A platform that reached dominance in search may have an incentive to limit services to consumers to be...

I characterize microfounded endogenous market structures with Bertrand and Cournot competition and perform welfare analysis generalizing the Mankiw-Whinston condition for excess entry. The impact of market leaders on welfare is reconsidered, with a number of policy implications about strategic...

Most market structures are neither perfectly or monopolistically competitive: they are characterized by a small number of large firms engaged in strategic interactions in their production and investment decisions. Yet, most of our economic theories are still based on a simplified world where...

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....

We survey the literature on the economics of eCommerce with particular emphasis on the antitrust debate about Amazon. The business model of such a hybrid marketplace is based on monetization through referral fees on third party sellers hosted on the platform and direct margins on own products....

We develop a simple model of competition for the market that shows that, contrary to the Arrow view, endogenous entry threat in a market induces the average firm to invest less in R&D and the incumbent leader to invest more. We test these predictions with a Tobit model based on a unique dataset...

Simple models of competition for the market with endogenous entry show that, contrary to the Arrow view, an endogenous entry threat in a market induces the average firm to invest less in R&D and the incumbent leader to invest more. We test these predictions based on a unique dataset and survey...