Deposit insurance, bank regulation, and narrow banking

Narrow banking has surfaced frequently as a proposed framework for dealing with financial instability and inefficiency. Recent proposals include reforms intended to improve the implementation of monetary policy, and to deal with perceived problems related to stablecoins. A model is constructed in which banks must deal with three frictions: limited commitment, moral hazard with respect to risky assets, and potential misrepresentation of safe assets. Surprisingly, deposit insurance does not engender inefficiency, and government-imposed capital requirements and leverage requirements serve to reduce welfare. The viability of narrow banking depends on inefficient regulation in conventional banking, and narrow banking is never welfare-improving.