Earnings Per Share

12 Months Ended

Dec. 31, 2021

We calculate basic and diluted earnings per share using the two-class method. Earnings per share under the two-class method is calculated using net income attributable to common stockholders, which is net income reduced by the earnings allocated to participating securities. Our participating securities include share-based payment awards that contain a non-forfeitable right to receive dividends and are considered to participate in undistributed earnings with common shareholders. Participating securities excluded from weighted average common shares outstanding were 268,000 for the year ended December 31, 2021.

The table below presents the computation of earnings per share, including the reconciliation of basic and diluted weighted average shares outstanding (in thousands, except per share data):


	Year Ended December 31,
	2021		2020		2019
Net income	$	650,624	$	366,738	$	261,575
Amounts allocated to participating securities	(4,321)		—		—
Net income attributable to common stockholders	$	646,303	$	366,738	$	261,575

Weighted average common shares outstanding:
Basic	39,876		40,106		39,833
Effect of dilutive securities:
Stock options and employee stock purchase plan	604		759		1,032
Diluted	40,480		40,865		40,865

Earnings per share attributable to common stockholders:
Basic	$	16.21	$	9.14	$	6.57
Diluted	$	15.97	$	8.97	$	6.40

Anti-dilutive stock options excluded from diluted earnings per share computations (1)	1		—		—

(1)Since these options have exercise prices that are higher than the average market prices of our common stock, including them in the calculation would have an anti-dilutive effect on earnings per share.