NOTE 3. NET INCOME (LOSS) PER COMMON SHARE

Basic net income (loss) per share is calculated by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is calculated by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period, plus dilutive common shares for the period determined using the treasury-stock method. For purposes of this calculation, options to purchase stock are considered to be potential common shares and are only included in the calculation of diluted net income (loss) per share when their effect is dilutive. Basic and diluted earnings per share are calculated as follows:

(in thousands, except for per share amounts)	Three Months Ended September 30,				Nine Months Ended September 30,
	2011		2010		2011		2010
Numerator:
Net income (loss)	$	(8,576)	$	1,891	$	84,563	$	2,188

Denominator for basic net income (loss) per share	55,372		52,595		54,268		52,445
Net effect of dilutive common stock equivalents	—		711		1,804		616
Denominator for diluted net income (loss) per share:	55,372		53,306		56,072		53,061


Basic net income (loss) per share	$	(0.15)	$	0.04	$	1.56	$	0.04
Diluted net income (loss) per share	$	(0.15)	$	0.04	$	1.51	$	0.04

For the three and nine months ended September 30, 2011, the total number of antidilutive outstanding common stock equivalents excluded from the net income per share computation was 4.9 million and 1.2 million, respectively. For the three and nine months ended September 30, 2010, the total number of antidilutive outstanding common stock equivalents excluded from the net income per share computation was 3.0 million and 3.4 million, respectively.