Net income per share attributable to common stockholders

Basic and diluted net income per common share is presented in conformity with the two-class method required for participating securities. The Company considers shares issued upon the early exercise of options subject to repurchase and non-vested restricted shares to be participating securities, because holders of such shares have a non-forfeitable right to dividends. Additionally, prior to the date of the Company's initial public offering (IPO) in June 2014, the Company considered its redeemable convertible preferred stock to be participating securities due to their non-cumulative dividend rights. Immediately after the completion of the Company's IPO, all outstanding shares of redeemable convertible preferred stock converted to Class B common stock.

The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to ten votes per share. Each share of Class B common stock is convertible at any time at the option of the stockholder into one share of Class A common stock and has no expiration date. Each share of Class B common stock will convert automatically into one share of Class A common stock upon the date when the outstanding shares of Class B common stock represent less than 10% of the aggregate number of shares of common stock then outstanding. Class A common stock is not convertible into Class B common stock.

Basic net income per share attributable to common stockholders is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. All participating securities are excluded from basic weighted average common shares outstanding. Diluted net income per share attributable to common stockholders is computed by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding, including all potentially dilutive common shares.

Undistributed earnings are allocated based on the contractual participation rights of common shares as if the earnings for the year have been distributed. As the liquidation and dividend rights are identical, the undistributed earnings are allocated on a proportionate basis. The computation of the diluted net income per share of Class A common stock assumes the conversion of Class B common stock.

The following table presents the calculations of basic and diluted net income per share attributable to common stockholders:



	Three months ended September 30,										Nine months ended September 30,
(in thousands, except per share data)	2015				2014						2015				2014
	Class A		Class B		Class A			Class B			Class A		Class B		Class A			Class B
Numerator:
Allocation of net income	$	13,849	$	4,950	$	2,395		$	12,225		$	46,561	$	24,021	$	417		$	5,411
Less: net income allocable to participating securities	—		—		(6		)	(30		)	—		—		(73		)	(949		)
Net income attributable to common stockholders—basic	13,849		4,950		2,389			12,195			46,561		24,021		344			4,462
Add: net income allocable to dilutive participating securities	—		—		1			4			—		—		10			130
Reallocation of net income as a result of conversion of Class B to Class A shares	4,950				12,195			—			24,021				4,462			—
Reallocation of net income to Class B shares	—		960		—			—			—		4,215		—			—
Net income attributable to common stockholders—diluted	$	18,799	$	5,910	$	14,585		$	12,199		$	70,582	$	28,236	$	4,816		$	4,592

Denominator:
Weighted-average common shares—basic	100,040		35,760		20,597			105,116			88,234		45,521		6,941			89,964
Conversion of Class B to Class A common stock outstanding	35,760		—		105,116			—			45,521		—		89,964			—
Effect of potentially dilutive shares	10,255		10,159		19,473			19,317			13,446		13,366		18,673			18,621
Weighted-average common shares—diluted	146,055		45,919		145,186			124,433			147,201		58,887		115,578			108,585

Net income per share attributable to common stockholders:
Basic	$	0.14	$	0.14	$	0.12		$	0.12		$	0.53	$	0.53	$	0.05		$	0.05
Diluted	$	0.13	$	0.13	$	0.10		$	0.10		$	0.48	$	0.48	$	0.04		$	0.04

The following potentially dilutive shares were not included in the calculation of diluted shares outstanding as the effect would have been anti-dilutive:



	Three months ended September 30,		Nine months ended September 30,
(in thousands)	2015	2014	2015	2014
Redeemable convertible preferred stock	—	—	—	20,237
Stock options, ESPP shares, and RSUs	2,373	366	1,993	2,871
Unvested restricted stock awards	—	308	2	376
	2,373	674	1,995	23,484