Yields on Fannie Mae and Freddie Mac mortgage securities that guide U.S. home-loan rates fell to the lowest relative to Treasuries in at least 25 years before retracing the move. The difference between yields on Washington-based Fannie Mae’s current-coupon 30-year fixed-rate mortgage bonds and 10- year Treasuries were unchanged at about 0.65 percentage point as of 5 p.m. in New York, after earlier falling to 0.63 percentage point to match the smallest spread since at least 1984…