Environmental Policy under Oligopoly with Endogenous Market Structure

Emission taxes under both fixed-number oligopoly and endogenous market structure, which are the most relevant market structures for policy issues, are examined. In the latter case, and contrary to what is expected under imperfect competition, the optimal tax could exceed marginal external damages, which implies that externalities generated by oligopolistic firms could be optimally controlled by overinternalizing environmental damages. Under endogenous market structure, a scheme consisting of a license fee and a second-best underinternalizing emission tax can increase social welfare as compared to the use of a single emission tax exceeding marginal damages.