A new source of risk for residential MBS has emerged in the wake of Wells Fargo’s recent decision to hold back significant funds from MBS transactions to cover potential litigation expenses resulting from investor claims. In its latest report, Moody’s Investors Service warned that trustee holdbacks, such as Wells Fargo’s action, have a negative effect on the MBS transactions. Such actions reduce, at least temporarily, the funds available to pay interest and principal to bondholders, the rating agency said. Last month, Wells Fargo notified...