A Model of Mortgage Default John Y. Campbell1 João F. Cocco2 This version: October 2011 First draft: November 2010 JEL classi…cation: G21, E21. Keywords: Household …nance, loan to value ratio, loan to income ratio, mortgage a¤ordability, negative home equity. 1 Department of Economics, Harvard University, Littauer Center, Cambridge, MA 02138, US and NBER. Email
[email protected]. 2 Department of Finance, London Business School, Regent’s Park, London NW1 4SA, UK, CEPR and Netspar. Email
[email protected]. We would like to thank seminar participants at the 2011 Spring HULM Conference, London Business School, the Federal Reserve Bank of Minneapolis, and the Rodney L. White Cen- ter for Financial Research at the Wharton School, and Andra Ghent, Francisco Gomes, Jonathan Heathcote, Pat Kehoe, Ellen McGrattan, Steve LeRoy, Jim Poterba, Nikolai Roussanov, Sam Schulhofer-Wohl, and Paul Willen for helpful comments on an earlier version of this paper. Abstract This paper solves a dynamic model of a household’sdecision to default on its mortgage, taking into account labor income, house price, in‡ation, and interest rate risk. Mortgage default is triggered by negative home equity, which results from declining house prices in a low in‡ation environment with large mortgage balances outstanding. Not all households with negative home equity default, however. The level of negative home equity that triggers default depends on the extent to which households are borrowing constrained. High loan-to-value ratios at mortgage origination increase the probability of negative home equity. High loan-to-income ratios also increase the probability of default by tightening borrowing constraints.