Had the government not provided Residential Credit with the ability to borrow most of the money it needed at low interest rates, agency officials said, the investors would have probably paid about 20 cents on the dollar less than they did.

Agency officials said the same kind of deal could be used to buy up troubled assets from banks that are still in business, which was the original purpose of the $700 billion Troubled Asset Relief Program. Since that program was approved by Congress last October, it has propped up banks, insurance companies, Wall Street firms and even car companies. But it has not been used to buy any troubled assets.

The main reason has been reluctance by both banks and investors, and some industry executives said they were still skeptical. Frank Pallotta, executive vice president of the Loan Value Group in Rumson, N.J., which provides analysis of mortgage values, said that many investors were worried about the strings attached to government-backed deals. One of the biggest strings is a requirement that the investors take part in the Obama administration’s Home Affordable Modification Program, which subsidizes loan modifications for borrowers at risk of losing their houses to foreclosure.

“The more active loan buyers are really not looking at these pools of loans,” said Mr. Pallotta. “I don’t think this sale is going to send investors off to the races.”

Officials said about 30 percent of the loans in the deal on Wednesday were nonperforming, meaning that payments were not being made on them, but said that percentage could increase depending on how much the houses being financed had dropped in value. About one-quarter of all homes are now under water, meaning that the property’s current market value is less than the mortgage.

Because homeowners have much less incentive to stay in houses that are under water, investors have become extremely dubious about mortgages in areas where housing prices have fallen sharply, even if most of the borrowers are still current on their payments.

The Obama administration has been working for months on two separate programs under the rubric of public-private partnerships to mop up the immense volume of bad assets tied to the housing bubble.