The Regulator's Trade-off: Bank Supervision vs. Minimum Capital

We develop a simple model of banking regulation with two policy instruments: minimum capital requirements and supervision of domestic banks. The regulator faces a trade-off: high capital requirements cause a drop in the banks’ profitability, while strict supervision reduces the scope of intermediation and is costly for taxpayers. We show that the expected costs of a banking crisis are minimised with a mix of both instruments. Once we allow for cross-border banking, the optimal policy is not feasible. If domestic supervisory effort is not observable, our model predicts a race to the bottom in banking regulation. Therefore, countries are better off by harmonising regulation on an international standard.