They've long enjoyed an implicit guarantee on their debt from the government.

FORBES: Rescuing Fannie And Freddie

Critics say the implicit guarantee of government backing that many investors believe comes attached to corporate debt enables inefficient companies to thrive by borrowing money at cheap rates.

WSJ: Faith in Bailouts Spurs China

The other, cleaner, approach would be to privatise them, so that the markets are left in no doubt that their debt carries no government guarantee, implicit or explicit.

ECONOMIST: Homesick blues

On reflection, perhaps you should think through your call to have more mortgage debt held by institutions with direct government guarantees and exposures, not to mention the efficacy of the implicit call for higher mortgage costs to American consumers.

ECONOMIST: Letters