Raman joined the company in April and was previously Senior Vice President, Global Sales and Operations. As COO, he will continue to report to Chief Executive Andrew Mason and oversee the company's global sales and operations, Groupon said.

Groupon lost two COOs when the company was growing at a ferocious pace leading up to its initial public offering late last year. Since then, growth has slowed to the point where many on Wall Street and beyond question the company's business model.

Groupon shares have lost more than three quarters of their value since the IPO. The stock hit record lows in recent days after the company reported disappointing third-quarter results as it struggled to turn around its European business.

Raman has been leading the re-organization efforts in Europe.

"We are already seeing progress in Europe and Kal will be instrumental in leading our company as we deploy tools and technologies that will help us continue to grow," Mason said.

Groupon shares gained 3.8 percent to $2.73 on Wednesday.

(Reporting By Alistair Barr; Editing by Gary Hill, Marguerita Choy and Tim Dobbyn)

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