Fitch Ratings announced last week that non-agency MBS with a unique structure will be eligible to receive AAA ratings. The rating service said deals with a shifting-interest structure are now eligible for the top ratings after previously limiting ratings on such deals to single-A. Both DBRS and S&P Global Ratings have assigned AAA ratings to some MBS backed by re-performing mortgages where the deals had shifting-interest structures. MBS with such structures distribute...