Net Income Per Share Attributable to Common Stockholders

The computations for basic and diluted net income per share attributable to common stockholders are as follows:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2012			2011			2012			2011
	(in thousands)
Numerator:
Net income	$	1,667		$	452		$	1,105		$	2,605
Net income attributable to participating securities	(1,252		)	(350		)	(841		)	(2,029		)
Net income attributable to common stockholders - basic	415			102			264			576
Undistributed earnings reallocated to participating securities	1,249			349			839			2,026
Net income attributable to common stockholders - diluted	$	1,664		$	451		$	1,103		$	2,602
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders - basic	5,843			5,137			5,540			5,002
Effect of potentially dilutive securities:
Convertible preferred stock	17,597			17,597			17,597			17,588
Common stock options	3,105			1,656			2,829			1,604
Warrants	—			—			—			2
Contingently issuable shares related to an acquisition	—			12			6			12
Weighted-average shares used in computing net income per share attributable to common stockholders - diluted	26,545			24,402			25,972			24,208
Net income per share attributable to common stockholders
Basic	$	0.07		$	0.02		$	0.05		$	0.12
Diluted	$	0.06		$	0.02		$	0.04		$	0.11

Potentially dilutive securities not included in the calculation of diluted net income per share because doing so would be antidilutive are as follows:



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2012	2011	2012	2011
	(in thousands)
Common stock options	1,108	2,806	1,031	2,828