Fitch Ratings has downgraded 1,186 bonds in 871 RMBS transactions that have had principal writedowns.
Fitch said it had issued ratings in the case of all the downgraded bonds that indicated defaults were expected.
Subprime credit collateral backed 290 of the downgraded, 286 were backed by prime credit collateral, 275 were backed by Alt-A credit collateral, and the 20 remaining were other unspecified types of transactions.