Twelve certificates from seven Credit Suisse First Boston mortgage-backed securities deals issued in 2002 and 2003 have been downgraded by Moody's Investors Service.Moody's also placed one certificate under review for possible downgrade. The negative rating actions were attributed to credit enhancement levels that are deemed to be low in view of projected losses on the underlying pools. "These pools of mortgages have seen high loss severities in recent months, and future losses could cause a more significant erosion of the overcollateralization in some cases," the rating agency said. CSFB Mortgage-Backed Pass-Through Certificates series 2002-5, 2002-18, and 2003-AR26 are backed by alternative-A mortgage loans, while CSFB Mortgage Securities Corp. series 2003-4, 2002-HE4, and 2002-HE16, along with CSFB Mortgage Acceptance Corp. series 2002-HE4, are backed by fixed- and adjustable-rate, first-lien subprime mortgage loans.
