We study competition in two sided markets with common network externality rather than with the standard inter-group e¤ects. This type of externality occurs when both groups benefit, possibly with different intensities, from an increase in the size of one group and from a decrease in the size of...

This paper studies a market for a medical product in which there is perfect competition among health insurers, while the good is sold by a monopolist. Individuals differ in their severity of illness and there is ex post moral hazard. We consider two regimes: one in which insurers use coinsurance...

This paper studies a market for a medical product in which there is perfect competition among health insurers, while the good is sold by a monopolist. Individuals differ in their severity of illness and there is ex post moral hazard. We consider two regimes: one in which insurers use coinsurance...