The regulatory reforms that followed the financial crisis of 2007-09 created a financial system that is far more resilient than the one we had 15 years ago. Today, banks and some nonbanks face more rigorous capital and liquidity requirements. Improved collateral rules for market-making activities can dampen shocks. And, some institutions are subject to well-structured resolution regimes.

Yet, the events of March 2023 make clear that the system remains fragile. The progress thus far is simply not enough. What else needs to be done?

In a new essay, we address this critical question. Our assessment of the banking system turmoil of 2023 leads us to several obvious conclusions, some of which clearly escaped both bank managers and their supervisors. Perhaps the simplest and most significant is that banks can survive either risky assets or volatile funding, but not both. Another is that supervisors are willing to treat some banks as systemic in death, but not in life.

We also draw two compelling lessons from the recent supervisory and resolution debacles. First, a financial system which relies heavily on supervisory discretion is unlikely to prove resilient. Second, authorities with emergency powers to bail out intermediaries during a panic will always do so. That is, policymakers are incapable of making credible commitments to impose losses on depositors and others. In our view, the only way to address this commitment problem is to prevent crises….