JPMorgan Chase was set to issue its latest jumbo mortgage-backed security as Inside Nonconforming Markets went to press. The bank’s sixth jumbo MBS of the year was slated to be a $344.87 million deal, according to presale reports. Chase continued to stock its jumbo MBS with loans that have seasoned a while longer than other issuers. Loans in JPMorgan Mortgage Trust 2015-6 had seasoned for an average of nine months, according to DBRS. Nearly 20 percent of the mortgages appear to have application dates from before Jan. 10, 2014. All of the loans subject to standards for qualified mortgages were deemed...