We explore how large and small banks make funding decisions when system-wide bailouts are possible. We show that bank size, purely on strategic grounds, is a key determinant of banks’ leverage choices, even when bailout policies treat large and small banks symmetrically. Large banks leverage more than small banks because they internalize that their decisions directly affect bailout policies. In equilibrium, this effect is amplified by strategic spillovers to small banks since banks’ leverage choices are strategic complements. Overall, the presence of large banks makes bailouts more likely. The optimal regulation features size-dependent policies that disproportionately restrict large banks’ leverage.

Recent reforms have given regulators broad powers to “bail-in” bank creditors during financial crises. We analyze efficient bail-ins and their implementation. To preserve liquidity, regulators must avoid signaling negative private information to creditors. Therefore, optimal bail-ins in bad times only depend on public information. As a result, the optimal policy cannot be implemented if regulators have wide discretion, due to an informational time-inconsistency problem. Rules mandating tough bail-ins after bad public signals, or contingent convertible (co-co) bonds, improve welfare. We further show that bail-in and bailout policies are complementary: if bailouts are possible, then discretionary bail-ins are more effective.