Note 13—Earnings Per Common Share

Basic and diluted earnings per common share are computed by dividing net income by the weighted-average number of basic and diluted common shares outstanding, respectively. The weighted-average number of diluted common shares includes the impact of dilutive securities, including outstanding stock options and unvested restricted stock and restricted stock units. The table below reconciles the weighted-average basic and diluted common shares outstanding:



	Three Months Ended September 30,		Nine Months Ended September 30,
	2018	2017	2018	2017
	(in thousands)
Weighted average number of common shares outstanding - basic	74,019	73,461	73,972	73,272
Effect of dilutive securities⁽¹⁾	560	1,077	626	980
Weighted average number of common shares outstanding - diluted	74,579	74,538	74,598	74,252

⁽¹⁾

Certain outstanding equity awards are anti-dilutive and were therefore excluded from the calculation of the weighted average number of diluted common shares outstanding. During the three and nine months ended September 30, 2018, stock options to purchase 0.6 million shares having a weighted average exercise price of $42.79 and $42.70 per share, respectively, were excluded. During the three months ended September 30, 2017, there were no anti-dilutive stock options, and during the nine months ended September 30, 2017, stock options to purchase 0.5 million shares having a weighted average exercise price of $39.38 per share were excluded. During the three and nine months ended September 30, 2018, 0.1 million restricted stock units were excluded. During the three and nine months ended September 30, 2017, there were no anti-dilutive restricted stock units.