4.	Net income (loss) per common share:

Basic net income (loss) per common share is computed by dividing the net income (loss) by the weighted average number of common shares outstanding for the period. Diluted net income (loss) per common share is computed by adjusting the numerator and denominator of the basic net income (loss) per share calculation for the potential impact of dilutive securities.

For the three and nine month periods ended September 30, 2017 , 2,214,110 and 2,128,751 stock options, respectively, were excluded from the calculation of diluted net income per common share as their inclusion would be anti-dilutive. For the three and nine months ended September 30, 2016, all stock options were anti-dilutive and were excluded from the diluted weighted average common shares outstanding for the period.

The following is a reconciliation of the numerators and denominators of basic and diluted net loss per common share:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Numerator:
Net loss used to compute net loss per common share:
Basic	$	(7,742	)	$	(7,714	)	$	(22,639	)	$	(16,993	)
Adjustment for change in fair value of liability classified stock options		(20	)		—			(182	)		—
Diluted	$	(7,762	)	$	(7,714	)	$	(22,821	)	$	(16,993	)
Denominator:
Weighted average number of common shares:
Basic		17,998,420			15,268,964			17,980,608			14,690,357
Adjustment for dilutive effect of stock options		11,559			—			19,458			—
Diluted		18,009,979			15,268,964			18,000,066			14,690,357
Net loss per common share - basic	$	(0.43	)	$	(0.51	)	$	(1.26	)	$	(1.16	)
Net loss per common share - diluted	$	(0.43	)	$	(0.51	)	$	(1.27	)	$	(1.16	)