Overborrowing and Systemic Externalities in the Business Cycle

Credit constraints linking debt to market-determined prices embody a systemic credit externality that drives a wedge between competitive and constrained socially optimal equilibria, inducing private agents to overborrow. This externality arises because private agents fail to internalize the financial amplification effects of carrying a large amount of debt when credit constraints bind. We conduct a quantitative analysis of this externality in a two-sector dynamic stochastic general equilibrium (DSGE) model of a small open economy calibrated to emerging markets. Raising the cost of borrowing during tranquil times restores constrained efficiency and significantly reduces the incidence and severity of financial crises.