CSFB MBS Classes Downgraded

Twelve classes from five issues of Credit Suisse First Boston Mortgage Securities Corp. mortgage-backed securities have been downgraded by Fitch Ratings.The downgrades were as follows: series 1997-2, class B-4, from B-plus to CC; series 2001-2, classes B-3 and B-4, from B to CC; series 2002-5 G4, class IVB2, from A to BBB, class IVB3, from A to BBB, class IVB4, from BBB to BB, and class IVB5, from CCC to C; series 2002-18 G2, class IIB3, from BBB-plus to BB, class IIB4, from BB to CCC, and class IIB5, from CCC to C; and series 2002-24 G1, class IB3, from BBB to BB, and class IB4, from CCC to C. In addition, Fitch upgraded 16 classes and affirmed the ratings on 28 others from 11 CSFB issues. The downgrades reflect the deterioration of credit enhancement relative to monthly losses, which have been consistent or rising, the rating agency said. The mortgage loans consist of fixed and adjustable-rate, 15- and 30-year mortgages extended to prime borrowers and are secured by first and second liens, primarily on one- to four-family residential properties.