Yields on Fannie Mae and Freddie Mac mortgage securities that guide home-loan rates climbed to the highest in five months relative to Treasuries as Europe’s worsening government finances led investors to shun all but the safest assets. Fannie Mae’s current-coupon 30-year fixed-rate mortgage bonds widened as much as 0.05 percentage point to about 0.78 percentage point more than 10-year Treasuries, the widest gap since Dec. 8, before closing at 0.75, according to data compiled by Bloomberg. The spread was 0.68 percentage point on April 26.