As delinquency and default continue to cycle through the securitization market,Fitch Ratings is taking action on 146 classes of Bayview Financial Trading Group's mortgage pass-through trust transactions. Ratings downgrades accounted for 44% -- or 64 -- of the 146 actions. Fitch also affirmed 70 pass-through trust transactions, while 12 ended up on rating watch negative. Bayview Financial either originated or acquired all of the mortgage loans in the transactions. The mortgage loans consist of fixed- and adjustable-rate, fully amortizing and balloon loans secured by senior liens on single-family, commercial, multifamily and mixed-use properties, according to Fitch. Of the '05 vintages, some faced downgrades from single- and double-A to double-and triple-B status. Fitch slashed two '05-vintage pass-through trust transactions previously placed on rating watch negative to double-C from triple-B and to single-D from double-B. Of the '06 vintages, many of the pass-throughs involved moved from double-A to triple-B, and from triple-B to triple-C. Several '07 pass-throughs fell all the way to triple-C from triple-A. There was a bit of good news, as the ratings agency said in a media statement that Bayview's earlier vintage transactions perform better than later vintages. For example, Fitch confirmed ratings of all of the '03 and '04 vintage classes, whereas affirmations account for 61%, 26% and 17% of the '05, '06 and '07 vintages, respectively. Write to Diana Golobay. Disclosure: The author held no relevant investment positions when this story was published. Indirect holdings may exist via mutual fund investments.