With the non-agency MBS market growing to new record levels in 2005, ratings surveillance resulted in some 1,417 upgrades and 150 downgrades, according to Standard & Poor’s. The 1,417 upgrades fell 10 short of 2004’s record. Prime jumbo transactions accounted for 64 percent of last year’s upgrades, subprime accounted for 17 percent and Alt A accounted for 12 percent. As has been the case recently, the upgrades were fueled by fast principal prepayments due to