Representations and warranties on new nonprime mortgage-backed securities often include weaknesses that limit their ability to protect investors against fraudulent or defective loans, according to an analysis by Moody’s Investors Service. However, the rating service said current practices and dynamics in the nonprime MBS market help to mitigate the risks from weak reps and warranties. Moody’s hasn’t placed ratings on nonprime MBS backed by ... [Includes four briefs]