Poisson-Cournot Games

We construct a Cournot model in which firms have uncertainty about the total number of firms in the industry. We model such an uncertainty as a Poisson game and we characterize the set of equilibria after deriving some novel properties of the Poisson distribution. When the marginal cost is zero, the number of equilibria increases with the expected number of firms ( n) and for n ≥ 3 every equilibrium exhibits overproduction relative to the model with deterministic population size. Overproduction is robust to sufficiently small marginal costs, however, for a fixed marginal cost, the set of equilibria approaches the equilibrium quantity of the deterministic model as n goes to infinity.