This paper explores the interrelationship between the net interest margin (NIM) and noninterest income and their determinants for banks in 9 Asian countries over the period 1998-2010. A simultaneous equations system is used to deal with endogenous regressors and its structural parameters are identified under a heteroskedastic covariance restriction, proposed by Lewbel (2012). The renovated Lerner Index proposed by Huang et al. (2013) is factored as a more robust proxy for market power over HHI. Our results demonstrate significantly positive relationship between the NIM and noninterest income, suggesting overall benefits for banks from income diversification. In addition, the loss-leader behavior is not supported in the sample countries.

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