Income per Common Share

3 Months Ended

Mar. 31, 2017

We compute basic earnings per share by dividing net income attributable to MPC by the weighted average number of shares of common stock outstanding. 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)	2017		2016
Basic earnings per share:
Allocation of earnings:
Net income attributable to MPC	$	30	$	1
Income allocated to participating securities	—		—
Income available to common stockholders – basic	$	30	$	1
Weighted average common shares outstanding	525		529
Basic earnings per share	$	0.06	$	0.003
Diluted earnings per share:
Allocation of earnings:
Net income attributable to MPC	$	30	$	1
Income allocated to participating securities	—		—
Income available to common stockholders – diluted	$	30	$	1
Weighted average common shares outstanding	525		529
Effect of dilutive securities	5		2
Weighted average common shares, including dilutive effect	530		531
Diluted earnings per share	$	0.06	$	0.003

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)	2017	2016
Shares issued under stock-based compensation plans	2	3