Oligopolistic competition as a common agency game

Oligopolistic competition is analyzed in a complete information multi-principal common agency framework, where principals are firms supplying differentiated goods and the agent is a representative consumer. We first propose a canonical formulation of common agency games, and a parameterization of the set of equilibria based on the Lagrange multipliers associated with the participation and the incentive compatibility constraints of each principal. This is used to characterize the set of equilibria in the intrinsic and non-intrinsic games. The former includes the latter, as well as the standard price and quantity equilibrium outcomes. It may also include the collusive solution.