WASHINGTON—Wall Street finally found reason to rally Thursday, soaring on a report that the Bush administration was considering setting up a government agency to soak up bad loans and mortgages. But it was far from clear that the government had settled on any solution to the worst crisis on Wall Street in decades.

The Dow Jones industrial average rose 410 points, recording its biggest percentage gain in nearly six years and adding to a week of extraordinary volatility in the American financial system and markets.

The rebound also came after an infusion of billions of dollars by the Federal Reserve and world governments aimed at getting nervous banks to stop hoarding money and lend again.

Stocks had fluctuated throughout the day, without severe swings in either direction, until CNBC reported the administration might back a new agency to take bad assets off the books of struggling financial institutions.

But a person with knowledge of the talks told The Associated Press that the idea, patterned after the Resolution Trust Corp. set up in the aftermath of the savings and loan crisis of the 1980s, was just one idea on the table.

The person, speaking on condition of anonymity because of the sensitivity of the discussions, said the talks had not narrowed to a single option, and that the RTC-style solution was not a certainty. Treasury Secretary Henry Paulson and Federal Reserve Chairman Ben Bernanke were scheduled to meet with key congressional leaders late Thursday night.

Before the sun rose on Wall Street, the Fed said it would boost by as much as $180 billion the amount of cash it would supply to foreign counterparts that are short on dollars. For banks in the United States, the Fed supplied $105 billion in short-term loans later in the day.

But, at least initially, those efforts did little to unfreeze the global credit markets. Banks remained extremely reluctant to lend money.

The No. 2 official at the International Monetary Fund, John Lipsky, said the past few days were “searing manifestations of a financial crisis that has expanded to historic proportions.” He predicted the turbulence would continue for “some time to come.”

The Fed said it had authorized the expansion of swap lines, the process by which it supplies reserves to other central banks, to include amounts up to $110 billion for the European Central Bank and up to $27 billion for the Swiss National Bank.

The Fed also said new swap facilities had been authorized with the Bank of Japan for as much as $60 billion, $40 billion for the Bank of England and $10 billion for the Bank of Canada.

For more than a year, investors around the world have watched with growing alarm as the U.S. economy, the world’s largest, has struggled to right itself amid massive home foreclosures, many of them from mortgages issued to homeowners with bad credit.

The turmoil has swallowed some of the most storied names on Wall Street. Three of its five major investment banks—Bear Stearns, Lehman Brothers and Merrill Lynch—have either gone out of business or been driven into the arms of another bank.

The Dow’s gain of nearly 4 percent on Thursday sent the average back above 11,000 and nearly erased its losses from a day before.