Yields on Fannie Mae and Freddie Mac mortgage securities that guide home-loan rates declined to the lowest in three weeks, signaling falling financing costs after a recent increase. Fannie Mae’s current-coupon 30-year fixed-rate mortgage bonds dropped about 0.02 percentage point to 4.43 percent as of 9:50 a.m. in New York, down from an eight-month high of 4.67 percent on April 5, according to data compiled by Bloomberg. Yields declined as benchmark Treasury rates retreated and premiums over 10-year government notes on mortgage-backed securities with U.S-supported guarantees held near record lows, withstanding the end last month of the Federal Reserve’s unprecedented purchases of $1.25 trillion of the bonds as investors’ demand for debt bolsters credit markets. “The Fed ended its MBS purchase program, and the world did not end,” Chris Flanagan and Tim Isgro, analysts in New York at Bank of America Corp., wrote in a weekly report April 9.