Freddie Mac bought $39 billion worth of loans in September, which is down from its $41.3 billion purchases in August. The agency saw its mortgage portfolio balance shrink again to an annualized rate of 9.4% in September, according to its monthly value summary report.

Freddie continues to shrink its presence in the mortgage sector after reducing its annualized rate of 5.5% in August and 8.7% in July.

Freddie modified 6,269 loans in September, down from 7,817 loans in August. Total modifications equal 49,683 as of 2012.

The unpaid principal balance on Freddie’s mortgage-related investment portfolio decreased by $5.4 billion in September.

The agency’s mortgage-related securities and other guarantee commitments also saw a decrease at an annualized rate of 10.4% in September.

Seriously delinquent single-family rate increased from 3.36% in August to 3.37% in September, according to summary. The multifamily delinquency rate decreased from 0.29% in August to 0.27% in September.

Single-family refinance-loan purchase and guarantee volume stayed the same at $29.2 billion in September, representing 75% of total mortgage portfolio purchases and issuance.

The measure of the agency’s exposure to changes in portfolio market value averaged $371 million in September, with a duration gap averaging one month.