Shares of Groupon Inc. (Nasdaq: GRPN) fell by as much as 17 percent Monday after the daily-deals provider disclosed a material weakness in financial reporting that prompted it to restate earnings numbers for 2011.

The shares closed at $15.27, down $3.10, or nearly 17 percent, having fallen to $15.25 earlier.

After markets closed Friday, the Chicago-based operator of Groupon.com disclosed in a regulatory filing that it would adjust fourth-quarter and full-year 2011 earnings. For the quarter ended Dec. 31, it trimmed revenue by about $14 million to $492.2 million, due to refunds to retailers that participated in Groupon deals.

As a result, the company's fourth-quarter net loss was $22.6 million, or 4 cents a share more than previously reported.

Groupon said it is working with its accountants to improve reports.

Last year the company's initial public offering was repeatedly delayed due to requirements by the U.S. Securities and Exchange Commission to adjust its financial reports. It was finally able to conduct its IPO on Nov. 5. The shares closed at $26.11 but quickly fell below their $20 offering price.

The company's market current capitalization is $9.74 billion.