Microfinance spillovers: A model of competition in informal credit markets with an application to Indian villages

Despite widespread interest in the development of microfinance, spillover effects on the non-using population and redistributive issues remain largely unexplored. I study a competition game between microfinance institutions (MFIs) offering joint-liability loans and moneylenders offering individual loans in presence of adverse selection. I show that one unintended consequence of the entry of a microfinance sector in local credit markets can be to trigger an increase in the equilibrium informal interest rate, because MFIs tend to attract a disproportionately-safe share of the borrower pool away from incumbent moneylenders. The existence of such composition externality depends crucially on the size of the microfinance sector and the risk composition of the borrower pool. The model predicts a non-linearly increasing relationship between informal interest rates and MFIs' capacity in relatively safe credit markets, and no relationship in risky villages. I show evidence supporting these predictions, using a first-hand panel database that records all credit transactions over 8 years for a sample of about 1000 households living in Indian villages with extensive space and time variation in the size of their microfinance sector.