Fannie Mae and Freddie Mac in the second half of last year saw a rapid growth of loans with high debt-to-income ratios, thanks in part to the so-called GSE patch. The government-sponsored enterprises enjoy a special exemption under the qualified mortgage rule of the Consumer Financial Protection Bureau. To achieve QM status, a loan must have a DTI ratio of 43 percent or less, but if a mortgage is sold to Fannie or Freddie, DTI ratios can be higher. In the second half of 2017, loans with DTI ratios ...