Freddie Mac (FRE.P) (FRE.N), the second-largest U.S. home funding company, on Friday said its mortgage investment portfolio grew by an annualized 65.8 percent rate in March, while delinquencies on loans it guarantees accelerated.

The portfolio increased to $867.1 billion, for an annualized 31.0 percent increase year to date, the McLean, Virginia-based company said in its monthly volume summary.

In March 2008, the portfolio was $712.5 billion.

The delinquencies that increased stress on the company's capital jumped to 2.29 percent of its book of business in March from 2.13 percent in February and 0.77 percent in March 2008.

Freddie Mac said the temporary suspension of foreclosures, which expired on March 6, contributed to the increase in single-family delinquency rates.

Freddie Mac said refinance-loan purchase volume was $52 billion in March, its largest refinance month since 2003.

The company's total mortgage portfolio increased at a 21.0 percent annualized rate in March to $2.247 trillion.

On Sept. 7, 2008, the U.S. government seized control of Freddie Mac and its larger sibling, Fannie Mae (FNM.N) (FNM.P). The takeover came amid heightened worries about shrinking capital at the congressionally chartered companies.

The government is now relying heavily on Fannie Mae and Freddie Mac in its efforts to stimulate the U.S. housing market, which is in the midst of its worst downturn since the Great Depression, by buying more mortgage loans, easing refinancing and helping homeowners avoid foreclosure.

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