In Europe, the Stoxx 600 Index ended the day with a 3.6 per cent gain to close at the highest level in nearly three months.
In afternoon trading in New York, the Dow Jones Industrial Average jumped 2.70 per cent, the Standard & Poor's 500 Index climbed 3.20 per cent and the Nasdaq Composite Index soared 3.36 per cent.
"You've got a lot of folks that were defensively positioned, many of whom were short different aspects of the market and they've got to reverse those bearish bets in light of what is actually happening," Orlando said.
The write-down that private owners of Greek bonds will accept allows both a 100 billion euro drop in the nation's sovereign debt and a new 100 billion euro lifeline for the embattled country, German Chancellor Angela Merkel said on Thursday.
"Our goal is that the debt of Greece by 2020 is 120 per cent [of GDP]," Merkel told journalists after a meeting of euro zone leaders, according to Reuters.
"A nominal haircut of 50 per cent has been agreed. On the basis of this, we will have a new program for Greece with a value of 100 billion euros."
The battered euro rallied as a result of the deal, rising as much as 2.3 per cent to US$1.4220. It last traded at US$1.4209.
The greenback dropped 1.87 per cent against a basket of its major counterparts.
"European leaders bought themselves several months of time at least," Brian Dolan, chief strategist in Bedminster, New Jersey at FOREX.com, told Bloomberg News. "Even before the summit, we had a push in the euro, down in the [US] dollar, up in all the risk currencies, higher in stocks. The bond market continued to take a pretty jaded view of all the goings on, and that has continued."
Among companies reporting earnings today were Dow Chemical and Exxon Mobil. Both stocks found approval among investors in today's cheerful environment, even as Dow Chemical's quarterly result didn't quite meet expectations.
Of 262 companies in the S&P 500 that have reported quarterly earnings, 72 per cent have exceeded Wall Street estimates, according to Thomson Reuters data.
Data showing the US economy expanded at its fastest pace in a year in the third quarter added to the optimism that a recession can be avoided. US gross domestic product rose at a 2.5 per cent annual rate in the third quarter, up from 1.3 per cent in the prior three months, the Commerce Department said.