Interest Rates and the Bank Risk-Taking Channel

The recent global financial crisis has brought the debate on how interest rates affect bank risk-taking to center stage. Proponents of this new risk-taking channel of monetary policy have argued that the low interest–rate environment in the run-up to the crisis may have created incentives for banks to take on excessive leverage and lower their lending standard, thus weakening bank portfolios. There is growing empirical evidence supporting this view. In contrast, this link has been little studied from a theoretical standpoint, leaving somewhat of a hole in our understanding of why (and how) banks’ decisions concerning the overall risk of their portfolios, and their capital structures, may be influenced by changes in the interest rate environment and, by extension, policy choices (e.g., monetary policy) that affect it. We summarize some of the emerging literature on this topic (both empirical and theoretical), as well as some of the more classical work on related topics. We also present a simple model that illustrates various channels through which bank risk-taking is affected by the interest rate environment in which banks operate. We use that model to analyze the likely effect of various other forces. Given the wealth of evidence that interest rates may have a real effect through banks’ portfolio decisions, it is important for policymakers to better understand the channel through which real interest rates operate on banks’ decision-making.