Yields on Fannie Mae and Freddie Mac mortgages

According to Bloomberg, “Yields on Fannie Mae and Freddie Mac mortgage securities that guide U.S. home-loan rates fell to the lowest in more than a year and many of their notes rose near record high prices as investors seeking safe debt wager prepayments will stay manageable.” See article link.  http://www.bloomberg.com/news/2010-06-22/fannie-mae-yields-that-guide-mortgage-rates-fall-to-lowest-level-in-a-year.html