[Update 1: Corrects volume of refinance purchases in June versus July]

Refinance activity dropped in July among loans purchased by mortgage giant Freddie Mac ($0.00 0%) as delinquencies rose among its single-family mortgages.

Freddie posted $44bn in purchases and issuances in July, from $63.1bn in June but up from $34.6bn in the year-ago period. Refinanced mortgages accounted for $34.1bn of purchases in July, down 33% from $50.9bn a month earlier.

Freddie's total mortgage portfolio, however, slipped at an annualized rate of 3.3% in July, according to the company's monthly volume summary.

The net amount of mortgage purchase or sales agreements made for Freddie's mortgage-related investments portfolio topped $11bn, up from $9.9bn last month. The aggregate unpaid principal balance of its mortgage-related investments portfolio fell to $799.1bn at the end of July from $829.8bn at the end of June.

But even as the unpaid principal balance fell within Freddie's mortgage-related investments portfolio, delinquencies rose 17bps among single-family loans.

The total single-family delinquency rate among Freddie's loans rose to 2.95% from 2.78% in June, while multifamily loan delinquencies held at 0.11% from last month. The rate of delinquency is up across the board from last year, when single-family loans were 1.01% delinquent in July 2008 and multifamily loans were 0.03% delinquent.

Write to Diana Golobay.

Disclaimer: The author held no relevant investments when this story was published.