Summary

The trade-off theory of capital structure says that corporate leverage is determined by balancing the tax-saving benefits of debt against dead-weight costs of bankruptcy. The theory was developed in the early 1970s and despite a number of important challenges, it remains the dominant theory of corporate capital structure.

The theory predicts that corporate debt will increase in the risk-free interest rate and if the tax code allows more generous interest rate tax deductions. Debt is decreasing in the deadweight losses in a bankruptcy. The equilibrium price of debt is decreasing in the tax benefits and increasing in the risk-free interest rate.

Dynamic trade-off models can be broadly divided into two categories: models that build capital structure into a real options framework with exogenous investments and models with endogeneous investment. These models are relatively flexible, and are generally able to match a range of firm decisions and features of the data, which include the typical leverage ratios of real firms and related data moments.

The literature has essentially resolved empirical challenges to the theory based on the low leverage puzzle, profits-leverage puzzle, and speed of target adjustment. As predicted, interest rates and market conditions matter for leverage. There is some evidence of the predicted tax rate and bankruptcy code effects, but it remains challenging to establish tight causal links.

Overall, the theory provides a reasonable basis on which to build understanding of capital structure.