主题：中国拒绝俄罗斯抛弃两房债券的要求，维护了美国的利益 -- 东方望天

Fannie Mae's debt obligations are treated as U.S. agency securities in the marketplace, which is just below U.S. Treasuries and above AAA corporate debt. This agency status is due in part to the creation and existence of the corporation pursuant to a federal law, the public mission that it serves. Fannie Mae's senior unsecured debt has been rated "AAA," "Aaa," and "AAA" respectively by Fitch, Inc., Moody's Investors Service, and Standard & Poor's.