Earnings per Share

The following table shows the information used in the calculation of our basic and diluted earnings per share calculation as of September 30, 2019 and September 30, 2018.



	For the Three Months Ended September 30,		For the Nine Months Ended September 30,
	2019	2018	2019	2018

Weighted average common shares outstanding for basic calculation	290,112,233	296,136,564	290,410,859	300,173,831
Add: Effect of stock options, deferred stock units and restricted stock units	15,063	8,889	11,492	4,873
Weighted average common shares outstanding for diluted calculation	290,127,296	296,145,453	290,422,351	300,178,704

Basic earnings per common share are calculated by dividing net income (loss) by the weighted average number of common shares outstanding, which includes 36,546 and 28,914 shares of participating securities in the three and nine months ended September 30, 2019, respectively, and 8,890 and 2,996 shares of participating securities in the three and nine months ended September 30, 2018, respectively. Diluted earnings per share are calculated by dividing net income (loss) by the sum of the weighted average number of common shares outstanding plus the additional common shares that would have been outstanding if potentially dilutive securities had been issued.

The weighted average common shares outstanding for the diluted earnings per share calculation excludes consideration of 1,303,854 and 1,203,220 equivalent shares in the three and nine months ended September 30, 2019, respectively, and 946,610 and 544,292 equivalent shares in the three and nine months ended September 30, 2018, respectively, as these shares are anti-dilutive. During the three months ended September 30, 2019, we repurchased 879,134 shares of our common stock under the previously announced repurchase program. These shares were subsequently retired.