Rising interest rates haven’t stopped JPMorgan Chase and Redwood Trust from working on new non-agency jumbo mortgage-backed securities with loans originated in the lower-rate environment. Chase’s security will include mortgages with an average age of four months, while the mortgages in Redwood’s jumbo MBS are about two months old. The weighted average gross coupon on mortgages in Chase’s $345.05 million non-agency jumbo MBS is 3.79 percent, well below the average 4.68 percent interest rate quoted ...