The aim of this paper is to test the predictions of Sutton's model of independent submarkets for the Italian retail banking industry. This industry, in fact, can be viewed as made of a large number of local markets corresponding to different geographical locations. In order to do that, I first develop a model of endogenous mergers that shows how the number of firms is determined by the initial number of firms, by the intensity of competition, and by the degree of product differentiation, and how this in turn affects the one-firm concentration index. Then, in the second part, the number of banks in each submarket is estimated using a truncated model and a Poisson model. The size of the submarkets turned out to be at most provincial. Finally,...