The Loan Store originated the largest portion of mortgages in the pool, 10.3%, according to Fitch, while an array of other lenders accounted for the rest.

Total consumer debt in the United States hit $18.2 trillion by the end of last year, with $12.8 trillion attributed to first mortgages, according to Equifax.

Underwriting relied heavily on alternative documentation, led by debt-service coverage ratios (35.7%) and bank statements ranging from 12-23 months (28.2%) and longer than 24 months (4.6%).