AN INTENSITY-BASED APPROACH TO THE VALUATION OF MORTGAGE CONTRACTS AND COMPUTATION OF THE ENDOGENOUS MORTGAGE RATE

This paper gives a general mortgage model subject to sub-optimal prepayment behavior of borrowers. The proposed classification of approaches to the option-based and mortgage-rate-based (MRB) specification is validated by the fact that these two approaches require different analytical and numerical tools. With the option-based specification of the prepayment intensity, our model is the first continuous-time model; this gives advantage in the numerical treatment of the model. We propose a new approach based on the MRB idea with the endogenous mortgage rate process. The mortgage rate process is defined and the existence of a solution is proven for the option-based specification of the prepayment process. A numerical procedure for finding the endogenous mortgage rate is proposed.