The riskiness of outstanding mortgages in the United States, 1999–2019

This article introduces measures of credit risk for all outstanding mortgages in the United States between 1999 and 2019. Terminations play a fundamental role in offsetting risk introduced by new originations because of refinance activity and the often dual nature of home buyers as concurrent sellers. To illustrate these concepts in a policy setting, I show that the Home Affordable Refinance Program increased origination risk metrics but reduced overall risk due to associated terminations of even riskier loans. In addition to these flow dynamics, amortization, loan age, collateral appreciation, and prior selection drive changes to portfolio-level risk.