Pricing the competing risks of mortgage default and prepayment in stochastic metropolitan economies

Abstract

Outlines previous research relevant to the risks involved in residential mortgages and suggests some reasons for the gap between theory and market practice. Develops a model which adds household income, ability to pay problems and mortgage underwriting constraints to the standard pricing models, using a combination of Monte Carlo simulation and the backward finite difference method to apply it to data on house prices, income and interest rates for 62 US metropolitan areas. Discusses the results which suggest that prepayment risk dominates default risk in all except very low growth housing markets. Adds that increasing loan‐to‐value levels decrease loan values in low growth markets, slightly increase them in high growth/low volatility markets (due to decline in prepayment risk), but have little impact on high growth/high volatility markets (because they are offset by changes in default and prepayment costs). Considers the practical implications of the findings, e.g. for portfolio managers.