For the revenue reduction - lowering the amount to $482.2 million from the previously reported $506.5 million -- the company, which went public in June, . CFO Jason Child, however, called the company "confident in the fundamentals of our business."

Discussing the material weakness statement, Groupon, whose independent auditor is Ernst & Young LLP, said it has been working in 2012 with "another global accounting firm," which it didn't identify. E&Y was involved with the completion of Groupon's audit at the end of the Dec. 31 year. A statement of material weakness in its internal controls was included in Groupon's 10-K.

Groupon "continues to implement process improvement initiatives and augment its staffing, and is expanding the accounting firm's engagement scope to address the underlying causes of the material weakness," it said in its statement yesterday.