Interactive Brokers Group, Inc. Annual Report (Amendment), Year Ended Dec 31, 2011

This filing is an amendment (10-K/A) to Interactive Brokers Group, Inc.'s (IBKR) 2011 Annual Report, filed in August 2012. The primary purpose of this amendment is to restate the company's consolidated financial statements for the three years ended December 31, 2011, due to accounting errors identified. Specifically, the restatement addresses an incorrect classification of redeemable noncontrolling interests and also corrects errors related to stock compensation awards and the recognition of equity award forfeiture provisions. Investors should note that the restatement impacts the classification of certain equity interests and the calculation of earnings per share, though it did not affect reported net income attributable to common stockholders or cash flows. Management identified a material weakness in internal controls over financial reporting related to the interpretation of complex accounting issues. This amendment provides updated financial statements and disclosures, and investors should rely on these restated figures for accurate financial assessment.