​Abstract:

To help inform the ongoing policy debate concerning the risks associated with second mortgages, the paper rigorously evaluates the effect of second liens on the performance of first mortgages.   Using a dataset that combines credit bureau information with mortgage performance data, the statistical analysis separately quantifies the extent to which piggyback and subsequent second liens impacted loan default and prepayment likelihoods for first liens.  In a simple direct comparison of first-lien outcomes, piggyback second liens are shown to have substantially increased mortgage default rates, while decreasing mortgage prepayment likelihoods.  The results differ significantly, however, when the relative comparison group is altered and the analysis looks for a “residual” relationship (i.e., the control variables are changed in the statistical analysis).   When first-lien outcomes are compared for borrowers with identical at-origination total equity and debt servicing obligations, the residual outcome differences tend to be minimal.  Where material differences do exist, piggyback second liens tended to be associated with marginally worse outcomes for loans originated during the housing boom and slightly better outcomes for later years.   With respect to subsequent second liens, models that evaluate the direct relationship between second liens and first-lien outcomes find a pronounced time trend.  In the late 1990s and early 2000s, the origination of a second lien generally signaled better subsequent performance for the associated first mortgage, most likely because only the most creditworthy borrowers were able to get such loans.   By the mid-2000s, the overall signal associated with subsequent second liens became negative—i.e., the underlying first mortgages performed materially worse than others.  An abrupt switch at the inception of the housing bust is then evident, however, as second-lien-burdened first mortgages then performed better again.  Models that control for total net equity and borrower debt obligations, i.e., seek the residual relationship between outcomes and second liens, show a consistent positive relationship between outcomes and subsequent second liens, but also reveal an interesting evolution over time.  The paper concludes with a comparison of time trends for various nonmortgage credit statistics—including nonmortgage loan balances, revolving credit utilization rates, and credit scores—for borrowers with and without second liens.