Evaluation of Mortgage Credit Risk

Abstract

This article describes a stochastic home price appreciation (HPA) model that can be used to obtain random paths of simulated home prices that are consistent with historical behavior and with market-implied HPA. The stochastic HPA model has been integrated with Citi’s prepayment, default, term structure, and MOATS models and can be used to calculate credit-adjusted option-adjusted spread (OAS) for non-agency mortgage-backed securities and loans. The credit-adjusted OAS model is available to users via the Yield Book.