6. Net loss per share

Basic and diluted net loss per common share are presented using the two-class method required for participating securities. If a dividend is paid on common stock, the holders of preferred stock are entitled to a proportionate share of any such dividend as if they were holders of common stock (on an if-converted basis). The Company considers its preferred stock to be participating securities and, in accordance with the two-class method, earnings allocated to participating securities and the related number of outstanding shares of participating securities have been excluded from the computation of basic and diluted net loss per common share.

The Company considers the Aquinox USA common stock to be their participating stock that is subordinate to all other stock or shares of the Company. These shares are used by the Company when computing its loss per share. Under the two-class method, net loss attributable to common stockholders is determined by allocating undistributed loss between common stock and participating securities. Undistributed loss is calculated as net loss less distributed loss, accretion of liquidation preference on preferred stock, accretion of share issuance costs on preferred stock, and tax expense on preferred stock. As holders of preferred stock, holders of stock options and holders of common stock warrants do not have contractual obligations to share in the losses of the Company, the net loss attributable to common stockholders for each period is not allocated between common stock and participating securities. Accordingly, outstanding stock options and common stock warrants were excluded from the calculation of basic and diluted net loss per share as the effect would have been anti-dilutive. There were no outstanding preferred stock for the three and six months ended June 30, 2015 and June 30, 2014. The detail of the computation of basic and diluted earnings per share is as follows:


	THREE MONTHS ENDED JUNE 30,						SIX MONTHS ENDED JUNE 30,
	2015			2014			2015			2014
*Numerator*
Net loss	$	(4,750	)	$	(5,424	)	$	(11,162	)	$	(9,653	)
Accretion for liquidation preference on preferred stock		—			—			—			(1,133	)
Accretion for share issuance costs on preferred stock		—			—			—			(20	)
Tax expense on preferred stock		—			—			—			(100	)
Reversal of tax payable on preferred stock due to conversion of preferred stock		—			—			—			1,898
Extinguishment of remaining share issuance costs due to conversion of preferred stock		—			—			—			(439	)

Total loss attributable to common stockholders	$	(4,750	)	$	(5,424	)	$	(11,162	)	$	(9,447	)

*Denominator*
Weighted average shares used to compute basic and diluted net loss per common share		10,723,584			10,675,260			10,717,808			6,606,091

Net loss per share attributable to common stockholders – basic and diluted	$	(0.44	)	$	(0.51	)	$	(1.04	)	$	(1.43	)

The following have been excluded from the computation of basic and diluted net loss per share as their effect would have been antidilutive:


	THREE MONTHS ENDED JUNE 30,				SIX MONTHS ENDED JUNE 30,
	2015		2014		2015		2014
Outstanding stock options		1,056,892		630,159		1,067,799		805,659
Common stock warrants		11,363		11,363		11,363		11,363

		1,068,255		641,522		1,079,162		817,022