Freddie Mac’s mortgage portfolio decreased at an annual rate of 3.5% in May as government officials continue to discuss how to transition to a mortgage market dominated by private capital. The GSE’s single-family refinance-loan purchase and guarantee volume hit $13.3 billion in May, representing 58% of total mortgage purchases and issuances, Freddie Mac said in its monthly volume update. Volume was $16.6 billion in April, 70% of all mortgage purchases and issuances. During the same period, Freddie’s mortgage-related securities and guarantee commitments fell at an annualized rate of 2.4%. In May, the GSE modified 8,891 loans, down from more than 11,000 modifications in April. When analyzing the five-month period ending in May, Freddie completed 55,398 loan mods. Meanwhile, the single-family seriously delinquent rate at Freddie fell to 3.53% in May, compared to 4.06% in May 2010. Multifamily delinquency rate declined to 0.38% from 0.4% in April, but was up from the 0.29% recorded in May 2010. Write to Kerri Panchuk.