Capital Market Frictions and Deposit Constraints at Banks

Following the investment-cash flow literature, we test whether bank lending is constrained by the availability of insured deposits--a necessary condition for the existence of a bank lending channel of monetary policy. We treat insured deposits as a type of "internal fund," similar to cash flows. We use a simple model to sort out the possible identification issues in interpreting the correlation between lending and deposit growth, including reverse causality and omitted-variable bias. To minimize the latter, we control for loan demand; we use Tobin's Q and other proxies. We also split the sample by capital ratios under the assumption that the frictions facing banks in capital markets should be most severe for poorly capitalized banks. The results are consistent with the existence of frictions in capital markets facing banks, and show that such frictions forge a link between the supply of bank loans and the supply of insured deposits. The frictions seem to matter only at small banks, suggesting that the potential for a bank lending channel is limited.