The European Union agreed on a 500 billion-euro ($670 billion) emergency fund in the early hours of Monday to protect highly indebted eurozone countries from the wolfpack of financial markets.
After 11 hours of talks, finance ministers settled on what they hoped would be a package big enough to prevent Greece's debt crisis from spreading, EU sources said.
The euro currency, which last week sank to a 14-month low against the dollar, rose nearly 2 percent in early trade in Asia and U.S. stock futures jumped 2 percent.
Gold prices, considered a safe haven investment, fell 1.5 percent after touching near record highs last week.
The EU plan was a mix of loans and loan guarantees, an EU diplomat said.
Earlier EU sources said the package would be worth 600 billion euros, including 100 billion euros of International Monetary Fund loans.
Ministers from Spain and Germany said euro zone countries would speed up their efforts to tackle their fiscal problems.
Financial markets have been punishing heavily indebted euro zone members, threatening to plunge them into Greece's plight.
The new safety net was meant to protect other countries with bloated budgets, such as Portugal, Spain and Ireland.
Jitters over euro zone finances have set global markets on edge and created the conditions for a nearly 1,000-point drop in the Dow Jones industrial average on Thursday, the trigger for which remains a mystery.
Moving swiftly to bolster Greece and instill confidence in shaky markets, the IMF approved a 30 billion-euro loan on Sunday as part of a broader combined EU-IMF rescue of the country totaling 110 billion euros. The IMF said 5.5 billion euros from the three-year loan would be disbursed immediately.
To secure the funds, Greece has committed to deep budget cuts that have already caused violent protests.
Today's strong action by the IMF to support Greece will contribute to the broad international effort underway to help bring stability to the euro area and secure recovery in the global economy, IMF Managing Director Dominique Strauss-Kahn said in a statement.
Policymakers around the globe are worried the crisis in Greece could spread to other countries, fears compounded by the unexplained shock plunge in U.S. stocks on Thursday.
U.S. lawmakers called for answers into the huge fall on Wall Street that left markets nervous.
Clearly the (U.S.) Securities and Exchange Commission needs to act, Senator Christopher Dodd, chairman of the Senate Banking Committee, told CBS television.
They need to step up very quickly and let us know what happened here and what steps need to be taken.
SEC Chairman Mary Schapiro will meet heads of key exchanges in Washington on Monday to discuss different trading rules that each employ, said a source familiar with the situation.
First it was thought a trading error triggered the plunge, but attention has turned to computer-driven trading platforms that can execute orders so fast they are hard to override.
Sources said the SEC was considering whether trading limits could be imposed across various markets for fast-falling stocks and possibly more circuit breakers.
In Europe, officials said they would fight speculative investors they blame for aggravating the public debt crisis.
We now see ... wolfpack behaviors, and if we will not stop these packs, even if it is self-inflicted weakness, they will tear the weaker countries apart, Swedish Finance Minister Anders Borg told reporters in Brussels before the EU meeting.
President Barack Obama and German Chancellor Angela Merkel spoke by phone about the importance of EU members acting to build confidence in markets.
Merkel suffered a electoral defeat when voters in state election deprived her of a majority in parliament's upper house after she angered many by agreeing to aid Greece.
Economists estimate that if Portugal, Ireland and Spain eventually come to require bailouts similar to Greece's, the total cost could be some 500 billion euros.
In a sign of the global concerns about the euro zone's crisis, finance officials from the G20 group of major developed and developing economies -- which include China and Brazil -- held a teleconference to discuss the crisis.
(Additional reporting by Jan Strupczewski, John O'Donnell and David Brunnstrom in Brussels and Lesley Wroughton in Washington; writing by Charles Dick and Tim Ahmann; editing by Chris Wilson)