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 a dynamic model with two competing durable goods; one dirty, the other clean. Due to network effects a consumer who adopts the dirty good today will increase the incentive future consumers have to adopt the dirty good. Thus, a consumer who chooses the dirty good, in a sense causes more...

We consider the effects of taxes for competing two-sided platforms. We first detail how a platform passes a tax increase on its prices. Adding price competition, we study next how the tax affects profits. Because of the strategic implications of the cross-side external effects, the tax increase...

We analyse a card payment system to assess the economic impact of the interchange fee. This fee is paid by the bank of the merchant, the acquirer, to the bank of the consumer, the issuer. We build up a mode in order to explore whether the interchange fee can enhance the participation to the...

In framework of Rochet and Tirole (2011), I allow for partial merchant internalization and study how MIT threshold is related to levels of inter-change fee that maximize various components of social welfare. I find that cost absorption on the side of issuers and merchant heterogeneity each bias...

A major result in the study of two-sided platforms is the strategic interdependence between the two sides of the same platform, leading to the implication that a platform can maximize its total profits by subsidizing one of its sides. We show that this result largely depends on assuming that at...