Nationstar Mortgage issued a $158 million non-agency mortgage-backed security this week with prime Alt A mortgages that have seasoned for an average of 11 years, according to a rating report from Standard & Poor’s. The AAA tranche had credit enhancement of 8.60 percent. Mortgages in the MBS had low or no documentation and 43.7 percent were cash-out refinances. S&P said 82.8 percent of the mortgages haven’t been delinquent in the last 24 months and the current ... [Includes one brief]