Groupon also confirmed on Thursday that it cut about 80 employees, mainly in sales, as part of an effort to automate and streamline the way its daily deals are sourced and distributed.
The company's shares slid to a record low of $3.25 in after-hours trading on Thursday, down 17 percent from their closing price of $3.92.
The darling of investors during last year's consumer dotcom IPO boom, Groupon has now shed four-fifths of its value since its public trading debut.
Wall Street has grown increasingly uneasy about the viability of its business as daily deals fever wanes among consumers and merchants, and as previously strong growth rates sputter.
Adding to the difficulties, the U.S. Securities and Exchange Commission has been inquiring into Groupon's accounting and disclosures, an area of controversy during its initial public offer.
Groupon's third-quarter revenue was $568.6 million, compared with $430.2 million in the year-ago period. Analysts were expecting revenue of $590 million, according to Thomson Reuters I/B/E/S.
It posted a quarterly net loss of $3 million, or zero cents per common share, compared with a net loss of $54.2 million, or 18 cents a share, in the third quarter of 2011.
Consolidated segment operating income, or CSOI, was at just over $50 million in the third quarter. Groupon forecast fourth-quarter CSOI between $30 million and $50 million.
Sameet Sinha, an analyst at B. Riley & Co, was expecting CSOI of $65.7 million in the third quarter and $67.7 million in the fourth quarter.
"CSOI was a big miss and Europe is taking it on the chin," Sinha said.
Andrew Mason, chief executive of Groupon, said on Thursday that a "solid performance" in North America was offset by "continued challenges" in Europe.
International revenue, which includes Europe, grew 3 percent to $277 million in the third quarter. North American revenue surged 80 percent to $292 million.
Europe has been a particular problem for Groupon, partly because the sovereign debt crisis has dented demand for higher-priced deals. Groupon was also offering steeper discounts, turning off some European merchants.
(Reporting By Alistair Barr; editing by Gary Hill, Andre Grenon and Matthew Lewis)
By Alistair Barr