Item 8.01. Other Events

Furnished as Exhibit 100 to this Current Report on Form 8-K are the following materials from CME Group Inc.'s Annual Report on Form 10-K for the year ended December 31, 2008, filed on March 2, 2009, formatted in XBRL (Extensible Business Reporting Language): (i) the Consolidated Balance Sheet, (ii) the Consolidated Statement of Income, (iii) the Consolidated Statement of Shareholders' Equity, (iv) the Consolidated Statement of Cash Flows and (v) the Notes to Consolidated Financial Statements. Users of this data are advised pursuant to Rule 401 of Regulation S-T that the financial information contained in the XBRL documents is unaudited and these are not the official publicly filed financial statements of CME Group Inc. The purpose of submitting these XBRL-formatted documents is to test the related format and technology and, as a result, investors and others should continue to rely on the official filed version of the filing and not rely on the XBRL-related documents in making investment decisions.

In accordance with Rule 402 of Regulation S-T, the information in this Current Report on Form 8-K, including Exhibit 100, shall not be deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liability of that section, and shall not be incorporated by reference into any registration statement or other document filed under the Securities Act of 1933, as amended, or the Exchange Act.