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 186,000 for the three months ended June 30, 2025, and 208,000 for the three months ended June 30, 2024, and 185,000 for the six months ended June 30, 2025 and 206,000 for the six months ended June 30, 2024.

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):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2025		2024		2025		2024
Net income	$	194,258	$	192,439	$	247,803	$	271,324
Amounts allocated to participating securities	(963)		(1,018)		(1,220)		(1,417)
Net income attributable to common stockholders	$	193,295	$	191,421	$	246,583	$	269,907

Weighted average common shares outstanding:
Basic	37,271		38,124		37,365		38,164
Effect of dilutive securities:
Stock options and employee stock purchase plan	136		201		155		235
Diluted	37,407		38,325		37,520		38,399

Earnings per share attributable to common stockholders:
Basic	$	5.19	$	5.02	$	6.60	$	7.07
Diluted	$	5.17	$	4.99	$	6.57	$	7.03

Anti-dilutive stock options excluded from diluted earnings per share computations (1)	190		56		190		57

(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.