According to an internal memo obtained by Reuters, Chris Muhr, SVP of sales, will now head the Europe, Middle East and Africa region, while Veit Dengler, SVP International, will be leaving the company.

The memo did not give any reason for Dengler's departure. He will be the latest in a slew of executives, including Lee Brown, who oversees national sales, who have left or decided to leave Groupon in recent months.

Fixing its European operations has become an imperative for Groupon after the second-quarter revealed big problems with that business, driving the company's already weak share price even lower.

In addition to the euro zone's sovereign debt crisis and economic slowdown, Groupon offered discounts that were too big, annoying some merchants in the region.

Groupon, one of a crop of consumer Internet companies that debuted on markets with much fanfare in late 2011, has lost more than three quarters of its market value since its initial public offering at $20 with CEO Andrew Mason, a music graduate, pummeled with questions about its ability to sustain revenue growth.

The stock now trades at $4.78.

Muhr hails from Citydeal, a company acquired by Groupon in 2010 as its entry into international markets. Along with Citydeal co-founders Emanuel Stehle, Jens Hutzschenreuter and Rajen Ruparell, he had moved to North America to improve sales in its domestic market ahead of Groupon's IPO.

"We've made great progress in the last few months, but we still have a lot of work to do, particularly in Europe," Groupon's operations chief Kal Raman said in the internal memo.

"While our challenges in Europe are no secret, after spending two weeks there, I am energized by the great team and clear opportunities to improve," he said.

(Reporting by Nivedita Bhattacharjee in Chicago; Editing by Edwina Gibbs)

• A Permanent Economic Emergency