Is perfect price discrimination really efficient? An analysis of free entry

We analyze models of product differentiation with perfect price discrimination and free entry. With a fixed number of firms, and in the absence of coordination failures, perfect price discrimination provides incentives for firms to choose product characteristics in a socially optimal way. However with free entry, the number of firms is always excessive. Our results apply to a large class of models of product differentiation. They also apply to models of common agency or lobbying with free entry and imply that one has excessive entry into the ranks of the principals.