The Effects of Entry under the Coexistence of Oligopolistic and Monopolistic Competition

This paper proposes a model of a continuum of industries in which some industries are monopolistically competitive, the others are oligopolistic, and they interact in a labor market. We use this model to examine the effects of an increase in the number of oligopolistic firms. We first show that this raises the equilibrium wage and induces exit of monopolistically competitive firms. Then, we find that the profits of each oligopolistic firm and the whole oligopolistic industry decrease. Finally, we establish that if the elasticity of substitution is the same in all industries, welfare improves as a result of an increase in the oligopolistic firms.