The effective regulation of banks requires identification of systemically important financial institutions. This column discusses a method to estimate the capital that a financial firm would need to raise if we have another financial crisis. This measure of capital shortfall is based on publicly available information but is conceptually similar to the stress tests conducted by US and European regulators.

How much capital should banks hold to cover their risk? This column argues that the preoccupation with capital rules misses a more fundamental concern. No amount of feasible regulatory capital can be an appropriate substitute for robust asset selection and valuation standards of banks.