We develop a theory of optimal bank leverage in which the benefit of debt in inducing loan monitoring is balanced against the benefit of equity in attenuating risk shifting. However, faced with socially costly correlated bank failures, regulators bail out creditors. Anticipation of this generates multiple equilibria, including one with systemic risk in which banks use excessive leverage to fund correlated, inefficiently risky loans. Limiting leverage and resolving both moral hazards—insufficient loan monitoring and asset substitution—requires a novel two-tiered capital requirement, including a “special capital account” that is unavailable to creditors upon failure

We document novel evidence on the spillover effect of a corporate control regulation on local mortgage markets. We find that banks directly targeted by the Sarbanes-Oxley Act (SOX) to rectify their internal control weaknesses reduce mortgage originations following the regulation’s enactment. This causes mortgage credit to be reallocated toward other banks in the same local markets: while competing public banks expand lending to safer borrowers, private banks increase lending toward risky applicants. Consequently, loans originated by private banks in spillover counties report higher default rates

Banks predominantly issue nondilutive CoCos, contrary to the suggestion that CoCos should be dilutive to reduce risk-taking. In an agency model of two moral hazards, we show that, although dilutive CoCos deter ex ante risk-taking and prevent banks from being undercapitalized, penalizing shareholders of a distressed bank with dilution leads to ex post risk-shifting. CoCos’ design and risk implications depend on bank capitalization: equity-constrained banks prefer nondilutive CoCos because they maximize the financing capacity by tackling ex post risk shifting only. Nondilutive CoCos can be used to implement the constrained social optimum for highly leveraged banks, and regulators can induce appropriate CoCo designs with capital regulations