Some classes of residential and commercial mortgage-backed securities are feeling the residual effects of Fitch changing its outlook on the nation’s sovereign debt rating. Fitch Ratings affirmed several U.S. credit ratings at AAA on Monday, while revising the nation’s overall long-term outlook to negative from stable. Because certain RMBS and CMBS finance deals benefit from government guarantees and insurance that comes from the U.S. government, Fitch said it will revise its ratings outlook on certain products from stable to negative. “While the vast majority of Fitch-rated U.S. structured finance transactions have little direct linkage to the U.S. government’s sovereign rating, certain transactions benefit from guarantees or insurance from the U.S. government (or U.S. government-related entities),” Fitch wrote in its notice. The company said outlook changes will impact 1,500 classes of student loan asset-backed securities, up to 100 classes of residential mortgage-backed securities and a small number of CMBS transactions. Fitch expects the changes will be revealed over the course of the next few days. Write to Kerri Panchuk.