Income (Loss) per Share

Basic income (loss) per share is computed by dividing net income (loss) by the sum of the weighted-average number of common shares outstanding and the weighted-average number of shares issuable under the common stock warrants, representing 354 thousand and 354 thousand shares during the three and six months ended June 30, 2019 and June 30, 2018, respectively. The common stock warrants are included in the calculation of basic income (loss) per share because they are issuable for minimal consideration. The following table sets forth the computation of basic and diluted income (loss) per share (in thousands, except per share amounts):



	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Net income	$	28,169	$	16,178	$	89,261	$	31,363
Less: Undistributed income allocated to participating securities (1)	324		242		1,021		433
Net income attributable to common stockholders	27,845		15,936		88,240		30,930
Plus: Net income effect of convertible securities	—		—		8,897		—
Numerator for diluted income per common share	$	27,845	$	15,936	$	97,137	$	30,930

Basic weighted-average common stock shares outstanding	49,960		45,684		49,529		45,659
Plus: dilutive effects of common stock equivalents	114		39		6,051		41
Diluted weighted-average common stock shares outstanding	50,074		45,723		55,580		45,700

Basic income per common share	$	0.56	$	0.35	$	1.78	$	0.68
Diluted income per common share	$	0.56	$	0.35	$	1.75	$	0.68

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(1)	Participating securities include restricted stock that has been issued but has not yet vested.

For each of the three and six months ended June 30, 2019, our calculation of diluted shares outstanding excluded 8 thousand shares of unvested restricted stock. Additionally, the calculation of diluted shares outstanding for the three and six months ended June 30, 2019 excluded 1.9 million and 1.8 million stock options, respectively. For the three and six months ended June 30, 2018, our calculation of diluted shares outstanding excluded 7 thousand and 27 thousand shares of unvested restricted stock, respectively. For each of the three and six months ended June 30, 2018, our calculation of diluted shares outstanding excluded 1.3 million stock options.

As discussed in Note 9—Debt, we have the option of settling the 5.00% Convertible Senior Notes in cash or shares of common stock, or any combination thereof, upon conversion. For the three and six months ended June 30, 2019 and June 30, 2018, diluted income (loss) per share was determined using the if-converted method. Our calculation of diluted shares outstanding for the three months ended June 30, 2019 and the three and six months June 30, 2018 excluded 5.6 million, 6.4 million, and 6.4 million common stock equivalents, respectively, as the effect would be anti-dilutive.