Earnings per Share

6 Months Ended

Jun. 30, 2021

12. Earnings per Share

Total outstanding shares as of June 30, 2021 and 2020, were 95.6 million and 94.5 million, respectively. Under our stock repurchase program, for the three and six months ended June 30, 2021, no shares were repurchased, and for the three and six months ended June 30, 2020, we repurchased and retired zero and 2.7 million shares, respectively. For the six months ended June 30, 2021 and 2020, we acquired 0.1 million and 0.2 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.

The number of our weighted-average shares outstanding for the three and six months ended June 30, 2021 and 2020 was as follows:


	Three Months Ended June 30,		Six Months Ended June 30,
(in millions)	2021	2020	2021	2020
Weighted-average number of shares of common stock outstanding - basic	95.5	94.5	95.3	95.3
Stock options	0.2	—	0.1	0.1

Restricted stock units	1.5	0.7	1.5	0.9
Weighted-average shares and assumed conversions - diluted	97.2	95.2	96.9	96.3

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 six months ended June 30, 2021, the number of anti-dilutive shares was approximately 8.1 million and 7.7 million, respectively. For the three and six months ended June 30, 2020, the number of anti-dilutive shares was approximately 7.9 million and 7.2 million, respectively