Fannie Mae said Wednesday that it sold $2 billion of short-term notes at its highest yields versus benchmark rates in a weekly auction since July 23.

The government-sponsored enterprise said that, to attract buyers, it sold $1 billion of three-month notes at a yield of 2.58%. That is about 89 basis points more than U.S. Treasuries and 23 basis points less than the three-month London interbank offered rate, compared with 76 basis points and 31 basis points in a sale last week.

Rising loan delinquencies and four straight quarterly losses have boosted the relative short-term borrowing costs for Fannie Mae, the nation's largest mortgage finance company, and Freddie Mac.

Treasury Secretary Henry Paulson has not detailed plans to support of the GSEs, leaving some bond buyers wary.

"Some buyers are backing away from the market, but in general I think money funds continue to buy and hold Fannie and Freddie debt," said Peter Crane, the president of Crane Data LLC, a company that tracks money market funds. "They assume the short-term money market debt will be safe and covered."

Fannie also sold $1 billion of six-month debt Wednesday at a yield of 2.87%, about 93 basis points above Treasury bills and 28 basis points below the six-month Libor rates, compared with 88 basis points and 31 basis points last week. Three-month Libor is currently set at 2.81%, while six-month Libor is at 3.12%.

Freddie raised $1 billion of one-month debt Wednesday at a yield of 2.28%, or 18 basis points more than one-month Libor.

Yield spreads on short-term notes sold by Fannie, Freddie, and the government-chartered Federal Home Loan banks, have been below historical averages this year.

"There's no other place to go, now that money funds are out of SIVs," Mr. Crane said. "A lot of people are looking at the rise in spreads as a godsend."

Sales of commercial paper by structured investment vehicles, halted in mid-2007 after buyers became concerned that some of the funds invested in bonds tied to subprime mortgages.

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