Agency Conflicts, Bank Capital Regulation and Accounting Measurement

We develop a model to show how shareholder-creditor agency conflicts interact with accounting measurement rules to influence the design of bank capital regulation. Relative to a benchmark autarkic regime, higher capital requirements mitigate inefficient asset substitution, but exacerbate underinvestment due to debt overhang. The optimal regulatory policy balances the distortions created by underinvestment and asset substitution, while also incorporating the excess cost of equity relative to debt financing for banks. The optimal regulatory policy can be implemented using historical cost accounting for low values of the excess cost of equity. For intermediate levels of the excess cost of equity, fair value accounting is necessary for regulation to optimally respond to interim performance signals by imposing higher capital requirements that mitigate asset substitution. If the excess cost of equity is sufficiently high, however, the optimal regulatory policy features forbearance by permitting asset substitution to mitigate underinvestment. Overall, our results highlight the importance of accounting measurement in influencing the design of bank regulation through the implementation of capital requirements.