Marathon Petroleum Corp | 2013 | FY | 3


Income per Common Share
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.
On June 30, 2011, 356,337,127 shares of our common stock were distributed to Marathon Oil stockholders in conjunction with the Spinoff. For comparative purposes, and to provide a more meaningful calculation for weighted average shares, we have assumed this amount to be outstanding for periods prior to the Spinoff in the calculation of basic weighted average shares. In addition, for the dilutive weighted average share calculations, we have assumed the dilutive securities outstanding at June 30, 2011 were also outstanding for periods prior to the Spinoff. Excluded from the diluted share calculation are less than one million, approximately two million and approximately four million shares related to stock-based compensation awards in 2013, 2012 and 2011, respectively, as their effect would be 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.
 
(In millions, except per share data)
2013
 
2012
 
2011
Basic earnings per share:
 
 
 
 
 
Allocation of earnings:
 
 
 
 
 
Net income attributable to MPC
$
2,112

 
$
3,389

 
$
2,389

Income allocated to participating securities
4

 
6

 
4

Income available to common stockholders - basic
$
2,108

 
$
3,383

 
$
2,385

Weighted average common shares outstanding
315

 
340

 
356

Basic earnings per share
$
6.69

 
$
9.95

 
$
6.70

Diluted earnings per share:
 
 
 
 
 
Allocation of earnings:
 
 
 
 
 
Net income attributable to MPC
$
2,112

 
$
3,389

 
$
2,389

Income allocated to participating securities
4

 
6

 
4

Income available to common stockholders - diluted
$
2,108

 
$
3,383

 
$
2,385

Weighted average common shares outstanding
315

 
340

 
356

Effect of dilutive securities
2

 
2

 
1

Weighted average common shares, including dilutive effect
317

 
342

 
357

Diluted earnings per share
$
6.64

 
$
9.89

 
$
6.67


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