Note 24: Earnings Per Share

We computed our basic and diluted earnings per common share as follows:

We computed our basic earnings per common share using net income available to common stockholders and the weighted average number of common shares outstanding during the period. We computed diluted earnings per common share using net income available to common stockholders and the weighted average number of common shares outstanding plus potentially dilutive common shares outstanding during the period. Net income available to participating securities was insignificant for all periods presented.

Potentially dilutive common shares from employee incentive plans are determined by applying the treasury stock method to the assumed exercise of outstanding stock options, the assumed vesting of outstanding restricted stock units, and the assumed issuance of common stock under the stock purchase plan. Potentially dilutive common shares are determined by applying the if-converted method for the 2005 debentures. However, as our 2009 debentures require settlement of the principal amount of the debt in cash upon conversion, with the conversion premium paid in cash or stock at our option, potentially dilutive common shares are determined by applying the treasury stock method. For further discussion on the specific conversion features of our 2005 and 2009 debentures, see “Note 19: Borrowings.”

For 2012, we excluded 29 million outstanding weighted average stock options (90 million in 2011 and 161 million in 2010) from the calculation of diluted earnings per common share because the exercise prices of these stock options were greater than or equal to the average market value of the common shares. These options could be included in the calculation in the future if the average market value of the common shares increases and is greater than the exercise price of these options. In 2012 and 2011, we included our 2009 debentures in the calculation of diluted earnings per common share because the average market price was above the conversion price. In 2010, we excluded the 2009 debentures from the calculation of diluted earnings per common share because the conversion option of the debentures was anti-dilutive. We could potentially exclude the 2009 debentures again in the future if the average market price is below the conversion price.