Debt contracts and stochastic default barrier

This thesis focuses on the theory of asset pricing models and their usage in the design of credit contracts. We describe the evolution of structural models starting from the basic Mertonian framework through the introduction of a default barrier, and ending with stochastic interest rate environment. Further, with the use of game theory analysis, the parameters of an optimal capital structure and safety covenants are examined. To the author's best knowledge, the first EBIT-based structural model is built up that considers stochastic default barrier. This set-up is able to catch the different optimal capital structures in various business cycle periods, as well as bankruptcy decisions dependent on the state of the economy. The effects of an exogenous change in the risk-free interest rate on the asset value, probability of default, and optimal debt ratio are also explained