JPMorgan Chase is close to selling a non-agency jumbo mortgage-backed security, according to traders and jumbo executives familiar with the company’s activities. Chase is treating the MBS as a test deal – which has been delayed – though it could close by the end of this month. A spokesman for Chase declined to comment on the matter but a source at the company confirmed that a deal is in the works. Chase might issue the deal as a private placement or the company might keep the security for its own portfolio and ...