This thesis focuses on the issue of bank funding structure and its implications for financial instability. The first chapter investigates how the dynamic interaction between the regulator and banks can endogenously lead to financial instability and generate boom-bust cycles. The model is able to capture pro-cyclical bank leverage, asymmetric credit cycles, and the Minsky moment in a unified framework. The second chapter provides a simple theoretical model to understand bank asset encumbrance and its implications for financial stability. I show that the effect of encumbrance depends on rates of over-collateralization faced by the banks, and I also demonstrate empirical evidence consistent with the predictions of the model. The third chapter revis...