Should banks be geographically diversified? Empirical evidence from cross-country diversification of European banks

Using a sample of European bank, this paper investigates the impact of banks' geographic diversification on their cost of equity capital. Examining the geographic diversification of European banks gives an insight on the value of cross-border banking. To measure diversification between major geographic areas in which the bank operates, the Herfindahl–Hirschman Index, based on revenues generated at home and abroad is constructed for each bank. To address the problem of endogeneity, system generalized method of moments estimator is used. The main finding of the analysis is that, other things equal, more geographic diversified banks have higher cost of equity capital than geographically focused ones. This result implies that the adverse market valuation effect of geographic diversification (increase in agency problem) dominates the positive ones (increase in efficiency and reduction in risk).