The total unpaid principal balance of subprime mortgages outstanding continued its slow decline in 2016, ending the year at an estimated $255.0 billion, according to Inside Nonconforming Markets. Subprime performance was mixed in the fourth quarter, with the share of loans past due increasing compared with the previous quarter, according to the Mortgage Bankers Association. Some 14.28 percent of mortgages were past due as of the end of the ... [Includes one data chart]