Investors should continue buying mortgage bonds tied to U.S. home loans because they are unlikely to suffer a wave of refinancings that would cut yields, according to JPMorgan Chase & Co. Congressional action would be required to trigger any significant “government-sponsored refi wave” in the market for bonds owned or guaranteed by mortgage financiers Fannie Mae and Freddie Mac, JPMorgan analysts led by Matthew Jozoff wrote in an Aug. 27 note to clients.