Green Mountain Coffee Roasters' stock surge likely has a big victim: David Einhorn's Greenlight Capital.
Einhorn told attendees of his annual investor event on Jan. 21 at the American Museum of Natural History in Manhattan that Greenlight still had a short position in the coffee company.
Green Mountain, long a favorite for hedge funds to bet against, got a major boost Wednesday when Coca-Cola announced that it would purchase a 10 percent minority stake in the company as part of a $1.25 billion deal.
Shares were trading around $80 late Wednesday. But the stock opened up more than 30 percent on Thursday at $108.
Einhorn's presentation to investors at the January event--over cocktails and hors d'oeuvres--didn't include the size of the Green Mountain position, according to an investor in attendance. But the billionaire investor made it clear that his firm continued to believe its thesis on the company being overvalued. Green Mountain was one of Greenlight's largest losers in 2013, according to the person.
Greenlight produced strong returns in 2013 regardless.
The flagship fund gained 19.1 percent net of fees for the year, according to a Jan. 21 letter to investors. Top long winners in the fourth quarter included Apple, General Motors, Marvell Technology Group and Micron Technology. Losing shorts include positions in the Japanese Yen, Chipotle Mexican Grill and U.S. Steel,according to the letter.
The letter makes no mention of Green Mountain. But an Oct.15 investor note said the Greenlight had added to its short position in the stock. In 2011, Einhorn famously criticized the company with a 110-slide presentation at the Value Investing Congress in New York City. That day, Oct. 17, shares ended trading at $82.50, almost exactly the same price as this week before the Coca-Cola news.
(Read more: Greenlight adds to coffee short, likes new iPhone)
A spokesman for Greenlight, Jonathan Gasthalter, declined to comment.
Others welcomed the Coca-Cola deal news.
"As the global innovator and leader in home carbonation, SodaStream views the announcement of Green Mountain Coffee Roasters partnership with Coca-Cola as further recognition that custom carbonation is the future of the $260 billion at-home carbonated beverage industry," the company said in a statement.
—By CNBC's Lawrence Delevingne. Follow him on Twitter @ldelevingne.