Eurozone leaders agreed a deal to help Greece last month
The euro has jumped and stock markets have risen on reports that eurozone leaders have agreed the details of a plan to rescue debt-ridden Greece.
Leaders had finally agreed an interest rate at which to lend money to Greece, should it be needed, the reports said.
As a result, the euro gained more than 1 cent on the dollar, to $1.3466, while the Athens stock exchange rose 3.4%.
This was despite the fact that leading ratings agency Fitch downgraded Greek government debt earlier on Friday.
Other leading European markets also gained ground, with the UK's FTSE 100 index up 1%, Germany's Dax gaining 1.3% and France's Cac 40 rising 1.8%.
The in US, the main Dow Jones index briefly breached 11,000 points for the first time in 18 months, before closing up 0.6% at 10,997.
The euro also rose slightly against the pound, to 87.630 pence.
Last month, the EU and IMF announced plans to provide a 22bn-euro (£20bn; $29.5bn) safety net that could be drawn on should Greece be unable to raise the funds it needs to pay off its debts.
But this did little to calm investors' nerves as few details of how the plan would work were revealed.
There were even concerns that disagreements between eurozone partners about the precise details of any rescue package may not be resolved.
As a result, the cost of borrowing on the financial markets for the Greek government kept on rising, reaching record levels of 7.5% on Thursday.
Reports now suggest that eurozone leaders have agreed a rate at which to lend money to Athens, which means it will not have to rely on raising funds in the financial markets.
This will be lower than the market rate, making it cheaper for Greece to borrow money.
Although Greece still maintains it does not plan to turn to its eurozone partners and the IMF for any loans, investors now believe it will have little choice.
Fitch downgraded Greece's credit rating by two notches, from BBB+ to BBB-, amid growing fears the country will not be able to resolve its debt problems without help.
The BBB- rating is significant, as this is the lowest rating that qualifies as an investment grade bond. Any further downgrade would mean Greece losing its investment grade status with Fitch.
Share prices in Athens have been hit by the uncertainty
If the two other major credit rating agencies, Standard & Poor's and Moody's, were to follow Fitch's lead, then a lot of big institutional fund managers, such as pension funds, would not be allowed to invest in Greek debt.
Greece is currently rated BBB+ by Standard & Poor's and A2 by Moody's.
The downgrade put more pressure on Greece to resolve its debt crisis quickly, and came as leading investors called for Greece to seek financial help.
"Now is the time to put some money on the table," John Stopford, co-head of fixed income at Investec, told the BBC.
"We are getting down to two options - an IMF package of financial support or organised debt restructuring."
His comments were echoed by Alistair Newton, strategist at Nomura Securities, who said it was "increasingly likely" that the Greek government would ask for a rescue from the EU and IMF.
A bail-out was likely to come before the end of May, he told the BBC.
The current volatility in the money markets would continue until that happened, he said, making Greece's current strategy of borrowing its way out of trouble unfeasible.