Earnings Per Share

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Earnings Per Share

Earnings Per Share

Basic earnings per share is computed by dividing net income attributable to CME Group by the weighted average number of shares of all classes of common stock outstanding for each reporting period. Diluted earnings per share reflects the increase in shares using the treasury stock method to reflect the impact of an equivalent number of shares of common stock if stock options were exercised and restricted stock awards were converted into common stock. Outstanding stock options of approximately 4,855,000 and 4,922,000 were anti-dilutive for the quarter and nine months ended September 30, 2012, respectively. Outstanding stock options of approximately 5,420,000 and 4,705,000 were anti-dilutive for the quarter and nine months ended September 30, 2011. There were approximately 838,000 and 850,000 anti-dilutive restricted stock awards for the quarter and nine months ended September 30, 2012, respectively. There were no anti-dilutive restricted stock awards for the quarter and nine months ended September 30, 2011.

	Quarter Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Net Income Attributable to CME Group (in millions)	$	218.0	$	316.1	$	729.5	$	1,066.4
Weighted Average Number of Common Shares (in thousands):
Basic	331,377		332,289		331,091		333,449
Effect of stock options and restricted stock awards	1,081		1,048		1,056		1,058
Diluted	332,458		333,337		332,147		334,507
Earnings per Common Share Attributable to CME Group:
Basic	$	0.66	$	0.95	$	2.20	$	3.20
Diluted	0.66		0.95		2.20		3.19