Stock indexes gave back some of their gains Monday and the euro turned lower against the dollar following a report that Germany and five other major European nations could risk having their credit ratings downgraded.

The Dow Jones industrial average jumped as much as 167 points Monday but gave up more than half of that gain in the afternoon. The Financial Times reported that Standard & Poor's might put the six nations on "creditwatch negative," which means there is a 50-50 chance that one might be downgraded in the coming months.

The Dow and S&P 500 rose in early trading on hopeful signs that Europe was making progress toward preventing a breakup of its 17-nation currency union. Yields on Italian government bonds receded sharply after the new government of Mario Monti introduced sweeping austerity measures over the weekend.

Also, the leaders of France and Germany called for a new European treaty to prevent nations from running up big debts like the ones that pushed Greece and other weak countries to the brink of default.

"There's pent-up demand, and people will use any excuse to get back in, thinking there's been too much pessimism," Gendreau said. Despite strong signals about the U.S. economy, the market has been weighed down by negative headlines about the U.S. budget impasse, credit-rating downgrades of the U.S. and other nations, and Europe's spreading crisis, Gendreau said.

The Dow was up 70 points, or 0.6 percent, at 12,089 at 2:30 p.m. Eastern. The Standard & Poor's 500 index rose 12, or 1 percent, to 1,256. The Nasdaq composite index rose 28, or 1.1 percent, to 2,655.

The gains were broad. All 10 industry groups in the S&P 500 rose. Financials stocks were among the biggest winners. Investors have feared that U.S. banks might be dragged down by their close connections to the unstable European financial system.

JPMorgan Chase & Co. jumped 3.5 percent, the most in the Dow. Bank of America was the second-biggest gainer of the Dow 30, rising 3.2 percent. Citigroup Inc. rose 5.7 percent, Morgan Stanley 6.1 percent.

Investors are hoping that a summit of European leaders on Thursday and Friday will produce concrete measures to prevent a messy breakup of the euro currency, which is shared by 17 nations. Markets have been jittery because of fears that the euro might disintegrate, causing a sharp recession in Europe that would spread through the world economy.

While the statements from French President Nicolas Sarkozy and German Chancellor Angela Merkel were far from a long-term solution, investors are eager to buy on any hint of good news because they have been earning meager returns from relatively low-risk investments such as Treasurys and CDs, said Brian Gendreau, investment strategist with Cetera Financial Group.

Italian bond yields dropped to their lowest level in a month, a day after the nation's new government introduced austerity measures. That suggests traders believe that Italy is far less likely to default. The main Italian stock index jumped 2.9 percent.

Italy's borrowing costs pulled back from a level that might have forced the nation to default. Analysts say bailing out Italy would be too costly and would hurt the credit standing of German and France, which have the strongest economies in the euro group.

The yield on the 10-year Italian bond plunged half a percentage point to 5.93 percent. It rose above 7 percent last month, a level at which other nations were forced to take bailouts. By comparison, bond yields in Germany, Europe's largest and most stable economy, are roughly 2 percent.

Monday's strong gains follow the best week in more than two years for U.S. stock indexes. The S&P 500 rose 7.4 percent last week, the most since March 2009. The Dow jumped 7 percent, the most since July 2009.

Markets are hopeful that, given the gravity of the situation afflicting the euro zone, the German and French leaders will come up with a common proposal for tighter integration on budget matters. Analysts say that such a plan could lead to further emergency aid from the European Central Bank, possibly through the International Monetary Fund.

In corporate news:

— Gannett Co. leapt 11.4 percent after the media company was upgraded to "buy" from "neutral" by analysts at Lazard Capital Markets.

— Incyte Corp. fell 2.7 percent after a Citigroup analyst downgraded the drug maker to "neutral" from "buy," saying its new blood-disease drug Jakafi might not work as a long-term treatment.

— SuccessFactors Inc. soared more than 50 percent after the company agreed to be sold to German software company SAP for $3.4 billion. SuccessFactors makes software specializing in human resources tasks. The deal is part of SAP's plan to compete with software rival Oracle Corp.