Securitized banking, procyclical bank leverage, and financial instability

Abstract

This paper provides a theoretical explanation of procyclical leverage of the broker-dealer sector and examines its macroeconomic consequences within the context of the securitized banking system characterized by loan securitization and collateralized short-term borrowing. First, from a model of repo transaction, it is shown that a broker–dealer (repo borrower)'s optimal leverage is positively related to asset prices. The main mechanism underlying this relation is a movement of repo rate, which reflects counter-party risks and collateral value risks repo lenders are facing. Second, based on this result, I develop a macroeconomic model with a securitized banking system characterized by procyclical bank leverage and identify conditions under which the model exhibits a limit cycle behavior. A vulnerability of the repo market to asset price fluctuations leads to procyclical bank leverage, which aggravates asset price cycles driven by the supply-led credit expansion and collapse. It is also found that as the procyclicality of bank leverage becomes stronger the financial cycles also get more intense and severe.