To date, permanent modifications that have occurred have typically involved a reduction in the interest rate, while reductions of principal balance have been quite rare. The preference by servicers for interest rate reductions could reflect familiarity with that technique, based on past episodes when most borrowers' problems could be solved that way.
But the current housing difficulties differ from those in the past, largely because of the pervasiveness of negative equity positions. With low or negative equity, as I have mentioned, a stressed borrower has less ability (because there is no home equity to tap) and less financial incentive to try to remain in the home.