Should policy makers be prevented from bailing out investors in the event of a crisis? I study this question in a model of financial intermediation with limited commitment. When a crisis occurs, the policy maker will respond with fiscal transfers that partially cover intermediaries' losses. The anticipation of this bailout distorts ex ante incentives, leading intermediaries to become excessively illiquid and increasing financial fragility. Prohibiting bailouts is not necessarily desirable, however: while it induces intermediaries to become more liquid, it may nevertheless lower welfare and leave the economy more susceptible to a crisis. A policy of taxing short-term liabilities, in contrast, can both improve the allocation of resources and promote financial stability.

We study how introducing a central bank digital currency affects equilibrium allocations and welfare in an environment where both currency and bank deposits are used in exchange. We highlight an important policy tradeoff: while a digital currency tends to improve efficiency in exchange, it may also crowd out bank deposits, raise banks’ funding costs, and decrease investment. We derive conditions under which targeted digital currencies, which compete only with physical currency or only with bank deposits, raise welfare. If such targeted currencies are infeasible, we illustrate the policy tradeoffs that arise when issuing a single, universal digital currency.

We study ex post efficient policy responses to a run on the banking system and the ex ante incentives these responses create. We show that the efficient response to a run is typically not to freeze all remaining deposits, since doing so imposes heavy costs on some individuals. Instead, once a run is underway, (benevolent) government institutions would allow additional deposit withdrawals, placing further strain on the banking system. When depositors anticipate these extra withdrawals, their incentive to participate in the run increases. In fact, ex post efficient interventions can generate the conditions necessary for a self-fulfilling run to occur.