Earnings Per Share

9 Months Ended

Sep. 30, 2019

12. Earnings per Share

Total outstanding shares as of September 30, 2019 and 2018, were 97.2 million and 102.7 million, respectively. Under our stock repurchase program, for the three and nine months ended September 30, 2019, we repurchased and retired 2.3 million and 7.0 million shares, respectively. For the three and nine months ended September 30, 2018, the shares repurchased and retired were 2.0 million and 6.0 million, respectively. For the nine months ended September 30, 2019 and 2018, we acquired 0.5 million and 0.6 million shares, respectively, related to tax withholding for share-based compensation.

The calculation of basic earnings per share of common stock is based on the weighted-average number of shares of common stock outstanding in the year, or period, over which they were outstanding. Our calculation of diluted earnings per share of common stock assumes that any shares of common stock outstanding were increased by shares that would be issued upon exercise of those stock awards for which the average market price for the period exceeds the exercise price less the shares that could have been purchased by the Company with the related proceeds, including compensation expense measured but not yet recognized.

Our weighted-average shares outstanding for the three and nine months ended September 30, 2019 and 2018 was as follows:



	Three Months Ended September 30,		Nine Months Ended September 30,
(in millions)	2019	2018	2019	2018
Weighted-average number of shares of common stock outstanding - basic	97.6	103.8	100.4	105.6
Stock options	0.4	1.1	0.4	1.1
Restricted stock units	0.9	1.0	1.1	1.2
Weighted-average shares and assumed conversions - diluted	98.9	105.9	101.9	107.9

Awards of potentially dilutive shares of common stock, which have exercise prices that were higher than the average market price during the period, are not included in the computation of dilutive earnings per share as their effect would have been anti-dilutive. For the three and nine months ended September 30, 2019, the number of anti-dilutive shares was approximately 5.0 million and 4.7 million, respectively, and for the three and nine months ended September 30, 2018, the number of anti-dilutive shares was approximately 3.8 million and 3.6 million, respectively.