Third-Degree Price Discrimination, Consumption Externalities, and Market Opening

This study investigates the effects of monopolistic third-degree price discrimination on market opening in the presence of consumption externalities between separate markets. Assuming symmetric interdependent linear demands and constant marginal cost, we indicate the possibility that with negative externalities a monopolist can do better by closing the relatively small market from the social welfare viewpoint, while it prefers opening that market if price discrimination is feasible. This result contradicts the previous literature on third-degree price discrimination and market opening which asserts that, in the case of non-increasing marginal cost, price discrimination improves social welfare if it opens new markets that are closed under uniform pricing.