Catastrophic Default and Credit Risk for Lending Institutions

Mortgage insurance does insure lenders against most ordinary default: that default induced by price movements in the overall housing market. However, private mortgage insurance typically excludes coverage of the truly catastrophic default resulting from such acts of God as fire, floods, earthquakes, and hurricanes, increasingly familiar in the United States in recent years. Often, these events affect a substantial portion of the houses within a particular neighborhood or region; and if disaster insurance or government aid is inadequate or nonexistent, the default is likely to occur, putting the credit institution at risk. This paper uses a two-state option model with an added jump process that accounts for the possibility and severity of a catastrophe. The paper then uses that information to determine the credit risk to a lender. In addition, this article goes beyond the standard market valuations typical of an option model in reporting the distribution of events that average up to the market cost of the lenders liability. This involves doing probability calculations not present in the usual valuation determinations of option pricing. The point of this article is that the option-pricing methodology provides the means for calculating such probability distributions, thus improving credit risk evaluations for the lender.