Fannie Mae, the largest U.S. home funding company, said on Wednesday it plans to sell $1 billion in three-year benchmark notes in a reopening of an existing 1.75 percent issue in its second issuance window in August.

The notes will mature on Aug, 10, 2012 and will be priced via a Dutch Internet-based auction on Wednesday.

Settlement is Aug. 28.

On Aug. 13, Fannie Mae sold $3 billion in new five-year benchmark notes to yield 43.5 basis points over comparable U.S. Treasuries. (Reporting by Caryn Trokie)