CSFB Mortgage-Backed Pass-Through Ctfs, Series 2002-22 Rated by Fitch.

Business Editors

NEW YORK--(BUSINESS WIRE)--July 31, 2002

CSFB Mortgage-Backed Pass-Through Certificates, Series 2002-22 classes III-A-1, IV-A-1, IV-X, IV-P and IV-PP ($215,612,500) certificates, are rated 'AAA' by Fitch. In addition, class D-B-1 ($2,479,449) certificate is rated

The 'AAA' rating on the classes III-A-1, IV-A-1, IV-X, IV-P and IV-PP senior certificates reflects the 2.62% subordination provided by the 1.12% class D-B-1 , the .75% class D-B-2, the .35% class D-B-3, the .20% class D-B-4, and the 0.10% class D-B-5. In addition, classes D-B-1, D-B-2, D-B-3, are rated 'AA', 'A', and 'BBB' respectively, based on their respective subordination.

Fitch believes the above credit enhancement will be adequate to support mortgagor defaults in the Group III and Group IV loans, as well as bankruptcy, fraud and special hazard losses in limited amounts. In addition, the ratings reflect the quality of the mortgage collateral and the strength of the legal and financial structures.

The Group III loans consists of 208 fully amortizing ten year seasoned 15 year fixed-rate, mortgage loans secured by first liens on one to four-family residential properties with an aggregate original principal balance of $35,072,948. The average unpaid principal balance as of the cut-off date is $168,620. The weighted average original loan-to-value ratio (LTV) was 66.13%. However, due to the seasoning the current weighted average LTV is 30.68%. Cash-out refinance loans represent 52.47% of the loan pool. The three states that represent the largest portion of the mortgage loans are California (43.54%), New York (14.61%), and New Jersey (8.52%).

The Group IV loans consists of 1,423 fully amortizing 30 year fixed-rate, mortgage loans secured by first liens on one to four-family residential properties with an aggregate original principal balance of $186,340,300. The average unpaid principal balance as of the cut-off date is $130,948. The weighted average original loan-to-value ratio (LTV) is 79.98%. Cash-out refinance loans represent 36.82% of the loan pool. The three states that represent the largest portion of the mortgage loans are California (19.02%), New York (12.29%), and New Jersey (9.51%). The loans in Group IV with an LTV greater than 50.00% at origination benefit from a loan level mortgage insurance policy issued by TGIC. The maximum amount of coverage under the policy is equal to 8.25% of the aggregate cut-off date principal balance, of the Group IV mortgage loans covered by the TGIC Policy.

The certificates are issued pursuant to a pooling and servicing agreement dated July 1, 2002 among Credit Suisse First Boston Mortgage Securities Corp., as depositor and Chase Manhattan Mortgage Corporation, as master servicer; and Bank One, NA, as trustee.