Moody’s Investors Service said it would not have given its highest rating to the jumbo mortgage-backed security issued last week by JPMorgan Chase because of concerns about the deal’s representation and warranty framework and the lack of risk retention by Chase. DBRS, Fitch Ratings and Kroll Bond Rating Agency gave JPMorgan Mortgage Trust 2013-1 AAA ratings with credit enhancement of 7.40 percent on the top-rated tranche. The rating services said the credit enhancement on the deal was ...