Fannie Mae said serious delinquencies on single-family mortgages slid in July from June, the fifth-straight month of declines, further signaling that home-loan problems were on the downswing.

A host of data have shown delinquencies easing this year as the U.S. economy heals. The number of serious delinquencies in Fannie's portfolio--loans at least 90 days behind for single-family homes--dropped in March from February, marking the first month-over-month decline in three years. They have been sliding ever since.

The rate fell to 4.82% in July from 4.99% in June, reaching a 10-month low.

Fannie's latest report also showed that its mortgage portfolio fell 0.3% in in August to $809.1 billion from July, shrinking at a 4.1% annual rate.