This study investigates the legitimacy of the relatively high interest rates charged by those microfinance institutions (MFIs) which have been transformed into regulated commercial banks using information garnered from a panel of 1232 MFIs from 107 developing countries. Results show that formally regulated micro banks have significantly higher average portfolio yields than their unregulated counterparts. By contrast, large-scale MFIs with more than eight years of experience have succeeded in

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... ering interest rates, but only up to a certain cut-off point. The implication is that policies which help nascent small-scale MFIs to overcome their cost disadvantages form a more effective pricing strategy than do initiatives to transform them into regulated institutions. JEL classification: G21; G23; G28; E43, N20