Single-family mortgages by Fannie Mae that have been in default for more than 60 days fell to 4.08 percent in June and July, the lowest level in two years.

Serious defaults had peaked in February 2010, when 5.59 percent of Fannie Mae’s $728 billion in mortgages had been in default for more than 60 days.

The decline arrives in the wake of new loan modifications that Fannie Mae has been offering its clients to avoid default. In the second quarter alone, Fannie re-worked more than 80,000 single-family loans, and 59,000 of them involved loan modifications, repayment plans and forbearances.

The modifications, though, have proved costly. Fannie Mae recently requested $5.1 billion in additional funds from the Treasury to offset its losses from modifications.

Fannie Mae President and CEO Michael J. Williams said that as a major provider of mortgages, Fannie is focused on long-term prospects for homeowners.

“We remain the largest source of liquidity for the U.S. mortgage market, and we are committed to creating long-term value by helping to build a stable, sustainable housing market for the future,” Williams said.