It's nice that Martin Feldstein recognizes the value of a serious program to address underwater mortgages. Unfortunately, this is the program:
If the bank or other mortgage holder agrees, the value of the mortgage would be reduced to 110 percent of the home value, with the government absorbing half of the cost of the reduction and the bank absorbing the other half. For the millions of underwater mortgages that are held by Fannie Mae and Freddie Mac, the government would just be paying itself. And in exchange for this reduction in principal, the borrower would have to accept that the new mortgage had full recourse — in other words, the government could go after the borrower’s other assets if he defaulted on the home. This would all be voluntary.
In other words, it wouldn't work. But thanks for playing.