Income per Common Share

3 Months Ended

Mar. 31, 2016

We compute basic earnings per share by dividing net income attributable to MPC by the weighted average number of shares of common stock outstanding. The average number of shares of common stock and per share amounts have been retroactively restated to reflect the two-for-one stock split completed in June 2015. Diluted income per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive.

MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities. Due to the presence of participating securities, we have calculated our earnings per share using the two-class method.



	Three Months Ended March 31,
(In millions, except per share data)	2016		2015
Basic earnings per share:
Allocation of earnings:
Net income attributable to MPC	$	1	$	891
Income allocated to participating securities	—		1
Income available to common stockholders – basic	$	1	$	890
Weighted average common shares outstanding	529		545
Basic earnings per share	$	0.003	$	1.63
Diluted earnings per share:
Allocation of earnings:
Net income attributable to MPC	$	1	$	891
Income allocated to participating securities	—		1
Income available to common stockholders – diluted	$	1	$	890
Weighted average common shares outstanding	529		545
Effect of dilutive securities	2		4
Weighted average common shares, including dilutive effect	531		549
Diluted earnings per share	$	0.003	$	1.62

The following table summarizes the shares that were anti-dilutive and, therefore, were excluded from the diluted share calculation.



	Three Months Ended March 31,
(In millions)	2016	2015
Shares issued under stock-based compensation plans	3	1