Corporate finance, collateralized borrowing, and monetary policy

We construct a monetary model in which entrepreneurs facing uncertainty in input costs and returns of projects may finance investment internally and with bank credit. Entrepreneurs using money as a down payment and bonds as collateral can reduce the default probability. Working through these key channels, lower nominal policy rates and open market sales can reduce the real lending rate. The central bank's private asset purchases improve availability of credit and compress risk spreads. Our model identifies the risk-reducing channel of private asset purchases-the policy functions as if the government had supplied more bonds, and the increased collateralizable bonds are allocated more to corporate borrowings with a higher lending risk. Risk-retention requirements associated with asset purchases are essential to welfare. As uncertainty with respect to input costs and investment returns intensifies, the central bank should lower the optimal risk-retention rate to encourage lending and reduce business failures.