Deep MI Gains Steam in 2Q Securitizations, S&P Reports After a bit of a slump, deep mortgage insurance appears to be making a comeback as a form of credit enhancement for subprime MBS issuers, a new report by rating agency Standard & Poor’s suggests. In an update on trends in the residential mortgage market, S&P said 41 percent of issuers included deep MI on their second-quarter subprime deals, up from 37 percent in the first