Instead, the programs together will likely help just an estimated one million homeowners.
Although the number of borrowers who owe more than the value of their houses is falling, it is the result of "foreclosures of severely negative equity properties rather than an increase in home values," according to CoreLogic, the Santa Ana, Calif., company that tracks the data.
Nationally, 10.8 million, or 22.5 percent, of residential properties with mortgages had negative equity, CoreLogic reported Monday. In metropolitan Philadelphia, the figure was 7.3 percent, or 66,282 properties.
The hardest-hit state, Nevada, had 67 percent of its properties underwater.
The principal reduction initiative requires servicers to consider mortgages eligible for HAMP that have what is described as "mark-to-market loan-to-value ratio" of 115 percent or more.
Mark-to-market refers to the value of an asset or liability based on its current market price. The figure of 115 percent means that if the house were sold at current market value, the borrower would still owe the lender more.
If the current value for a property with a loan being modified under the program is more than the balance owed, servicers are encouraged to offer the borrower a chance to reduce the principal as well as the opportunity to refinance the mortgage at a lower rate.
To accommodate lenders, the Federal Housing Administration launched what it called a "Short Refi" program to place underwater borrowers in new government-insured mortgages if the lender or investor writes off the unpaid principal balance of the original first mortgage by at least 10 percent.
The Treasury Department set aside $14 billion for the short-refinance program.