In a model with bankruptcy costs and segmented deposit and equity markets, we endogenize the cost of equity and deposit finance for banks. Despite risk neutrality, equity capital earns a higher expected return than direct investment in risky assets. Banks hold positive capital to reduce bankruptcy costs, but there is a role for capital regulation when deposits are insured. Banks could no longer use capital when they lend to firms instead of investing directly in risky assets. This depends on whether the firms are public and compete with banks for equity capital or are private with exogenous amounts of capital.