A subprime mortgage-backed security of seasoned mortgages was rated as AAA by Standard & Poor’s last week, prompting complaints and comparisons to S&P’s recent downgrade of the rating for the U.S. government. S&P notes that the securitization by Springleaf Financial includes a number of unique characteristics and that sovereign ratings are not directly comparable with MBS ratings. S&P assigned AAA ratings to a portion of Springleaf’s $496.86 million subprime MBS. The AAA tranches had an exceptionally high 41.15 percent credit enhancement and more than 98.0 percent of the mortgages in the deal are current, according to S&P. ...