Who takes the hit on loan principal reduction?

[Don Levy]

There is a talk about reducing borrower's principal on their loans to help them stave off foreclosure. I would like to know who has to take the hit when a loan is reduced. Most lenders package their loans and sell them to bigger companies, so are these companies who bought the loans in good faith going to have to take the hit?
A lot of loans are sold to investors who acted in good faith. Are they going to get zapped?
Maybe the loans that are going to be reduced will be sold back to the originators. This makes the most sense. Does anyone know the answer to this question?