Rating services are putting considerable energy into assessing the companies that are originating loans for the new breed of jumbo non-agency MBS, in addition to thorough due diligence reviews of the collateral itself, industry experts say. The rating services don’t even begin the rating process until the major loan originators in a transaction clear the “gating” process, said Kathryn Kelbaugh, a senior analyst at Moody’s Investors Service, during a panel session at last week’s secondary market conference sponsored by the Mortgage Bankers Association. “We want to know what originators are doing, have third-party reviews and look at reps and warranties. You have to pass those gates before we can do a rating.” Margaret Sweeney, a director at Fitch Ratings, said...