We estimate a dynamic investment model in which firms finance with equity, cash, or debt. Misvaluation affects equity values, and firms optimally issue and repurchase overvalued and undervalued shares. The funds flowing to and from these activities come from investment, dividends, or net cash. The model fits a broad set of data moments in large heterogeneous samples and across industries. Our parameter estimates imply that misvaluation induces larger changes in financial policies than investment. The investment responses are strongest for small firms but nonetheless modest. Managers' rational responses to misvaluation increase shareholder value by up to 4%.

We quantify the importance of collateral versus taxes for firms' capital structures. We estimate a dynamic model in which a taxable firm seeks financing for investment, and a dynamic contracting environment motivates endogenous collateral constraints. Optimal leverage stays a safe distance from the constraint, balancing the tax benefit of debt with the cost of lost financial flexibility. We estimate this flexibility cost to be 7.2% of firm assets, a percentage that is comparable to the tax benefit. Models with different tax rates fit the data equally well, and leverage responds to the tax rate only when taxes are low.