Impact of Mergers on the Degree of Competition : Application to the Banking Industry

This paper analyses the relation between competition and concentration in a monopolistic competition model where banks compete in branching and interest rates and market structure is endogenous. The model is applied on individual bank data in Italy and France using a maximum likelihood approach to derive a measure of the degree of competition in each local market. We propose an empirical test to evaluate ex-ante the impact of horizontal mergers on this measure. Depending on the pre-merger market structure and geographic distribution of branches, we find either cases where the merger is pro-competitive or anti-competitive. It proves its relevance as a tool for competition policy analysis. In addition, thanks to its theoretical foundation, it encompasses more information than traditional measures of competition while it is parsimonious in terms of data requirements