The determinants of bank margins revisited: a note on the effects of diversification

Most of the theoretical and empirical literature on bank margins has dealt solely with interest margins. Applying the seminal Ho-Saunders model (JFQA, 1981) to a multi-output framework, we show that the relationship between bank margins and market power (controlling for risk) varies significantly across bank specializations. Using a set of both accounting margins and New Empirical Industrial Organization (NEIO) margins, we find that market power rises significantly with output diversification to wards non-traditional activities. These results contribute to explain the paradoxical coexistence of decreasing interest margins and higher market power found in previous studies.Financial support from the Spanish Savings Banks Foundation (FUNCAS) and MCYT-FEDER, SEC2002-00348