The paper analyzes the change in the size distribution of Italian banking groups over the period 1999 to 2007 following a wave of M&As among large banks. Had this process increased the degree of concentration we would have expected greater credit rationing for small firms, given the central role of Italian banks in financing small firms. We measure this change through widely used measures of concentration on branches. First, we observe a steady increase in concentration that can be captured only by looking at the overall size distribution. Other measures do not perceive this change until the year 2007, when the very large banks merged. Second, by focusing on the banking groups that have been active players in M&As we do see a decline in concentration, since smaller players have caught up with the larger ones in terms of rate of size increase. This contrasts with the role of the new entries and the disappearance of banks following mergers, that has increased the dispersion of market shares. The implications are that: i) there is a credit termination risk due to the rise in active players’ size, but ii) credit rationing may not occur due to a substitution effect in credit supply from new entries.