CSFB MBS Classes Downgraded

Three classes of subordinated tranches from three mortgage-backed securitizations issued in 2002 by Credit Suisse First Boston Mortgage Securities Corp. have been downgraded by Moody's Investors Service.The downgrades were as follows: series 2002-AR8, class C-B-4, from Ba3 to B1; series 2002-AR28, class III-M-2, from A2 to Baa2; and series 2002-AR31, class VII-M-2, from A2 to Baa2. In addition, Moody's upgraded 35 classes of mezzanine and subordinated tranches from nine CSFB transactions and confirmed the rating of one subordinate tranche. The downgraded classes "suffer primarily from the performance of the underlying loans, with cumulative losses exceeding our original expectations," Moody's said. The pools are jumbo-A/alternative-A first-lien adjustable-rate loans. The rating agency can be found on the Web at http://www.moodys.com.