Earnings (Loss) Per Share

The Company computes basic earnings (loss) per share by dividing net income (loss) by the weighted-average common shares outstanding during the period. Diluted earnings (loss) per share is calculated to give effect to all potentially dilutive common shares that were outstanding during the period. Weighted-average diluted common shares outstanding primarily reflect the additional shares that would be issued upon the assumed exercise of stock options and the assumed vesting of unvested share awards. The treasury stock method has been used to compute diluted earnings (loss) per share for the three and nine months ended September 30, 2019 and 2018.

The Company issued warrants that represent the right to purchase shares of Common Stock, Stock Appreciation Rights (“SARs”) and Restricted Stock Awards (“RSAs”), all of which have been evaluated for their potentially dilutive effect under the treasury stock method. See Note 3. Weichai Transactions herein for additional information on the Weichai Warrants and Note 12. Stock-Based Compensation in the Company’s 2018 Annual Report for additional information on the SARs and the RSAs.

The computations of basic and diluted earnings (loss) per share are as follows:



(in thousands, except per share basis)	For the Three Months Ended September 30,					For the Nine Months Ended September 30,
	2019		2018			2019		2018
Numerator:
Net income (loss)	$	5,756	$	(18,819	)	$	172	$	(44,828	)

Denominator:
Shares used in computing net income (loss) per share:
Weighted-average basic shares outstanding	22,849		18,625			21,064		18,567
Effect of dilutive securities	27		—			24		—
Weighted-average common shares outstanding – diluted	22,876		18,625			21,088		18,567

Earnings (loss) per common share:
Earnings (loss) per share of common stock – basic	$	0.25	$	(1.01	)	$	0.01	$	(2.41	)
Earnings (loss) per share of common stock – diluted	$	0.25	$	(1.01	)	$	0.01	$	(2.41	)

The aggregate number of shares excluded from the diluted earnings (loss) per share calculations, because they would have been anti-dilutive, were 0.2 million and 1.8 million shares during the three and nine months ended September 30, 2019, respectively and 3.6 million and 3.9 million shares during the three and nine months ended September 30, 2018, respectively.