INCOME PER COMMON SHARE

We compute basic earnings per share by dividing net income attributable to MPC less income allocated to participating securities by the weighted average number of shares of common stock outstanding. Since MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities, we have calculated our earnings per share using the two-class method. Diluted income per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive.



(In millions, except per share data)	2018		2017		2016
Basic earnings per share:
Allocation of earnings:
Net income attributable to MPC	$	2,780	$	3,432	$	1,174
Income allocated to participating securities	1		2		1
Income available to common stockholders – basic	$	2,779	$	3,430	$	1,173
Weighted average common shares outstanding	518		507		528
Basic earnings per share	$	5.36	$	6.76	$	2.22
Diluted earnings per share:
Allocation of earnings:
Net income attributable to MPC	$	2,780	$	3,432	$	1,174
Income allocated to participating securities	1		2		1
Income available to common stockholders – diluted	$	2,779	$	3,430	$	1,173
Weighted average common shares outstanding	518		507		528
Effect of dilutive securities	8		5		2
Weighted average common shares, including dilutive effect	526		512		530
Diluted earnings per share	$	5.28	$	6.70	$	2.21

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



(In millions)	2018	2017	2016
Shares issuable under stock-based compensation plans	—	1	3