We show that if firms in an industry engage in third-degree price discrimination, the number of firms in the free-entry equilibrium may be inefficiently low. This result is obtained even with set up costs and a price above marginal cost. We discuss the relevant implications that our result has...

It has been proved that in an homogeneous product industry, price over marginal costs, business stealing, set up costs and free entry imply excess entry from the welfare point of view. The proof assumes identical firms. We show by example that with non-identical firms, those conditions are...