Traditional theory suggests that more profitable banks should have lower risk-taking incentives. Then why did many profitable banks choose to invest in untested financial instruments before the crisis, realizing significant losses? We attempt to reconcile theory and evidence. In our setup, banks are endowed with a fixed core business. They take risk by levering up to engage in risky ‘side activities’(such as market-based investments) alongside the core business. A more profitable core business allows a bank to borrow more and take side risks on a larger scale, offsetting lower incentives to take risk of given size. Consequently, more profitable banks may have higher risk-taking incentives. The framework is consistent with cross-sectional patterns of bank risk-taking in the run up to the recent financial crisis.

"This thesis is an attempt to explain methods of determining the investment worth of bank stocks. It is assumed that the chief interest of most investors is profit making; therefore, investment worth may be taken to mean income- and wealth-producing power. There are some instances in which bank stocks are bought for purposes other than profit, as when control of a bank's management is desired, but such instances are not included in this objective study of investment worth. The Chicago banks were used as subjects of special study because easier and better access could be had to information concerning these banks than to any other group of banks."--P. i.