Loss per Common Share

12 Months Ended

Dec. 31, 2016

3. Loss per Common Share

Basic loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per common share is computed by dividing (a) net loss, less any anti-dilutive amounts recorded during the period for the change in the fair value of warrant liabilities, by (b) the weighted-average number of common shares outstanding for the period plus dilutive potential common shares as determined using the treasury stock method for options and warrants to purchase common stock.

The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts):

	Year Ended December 31,
	2016			2015			2014
Numerator:
Net loss—basic	$	(38,023	)	$	(36,676	)	$	(43,002	)
Adjustment for change in fair value of warrant liability		—			—			(3,892	)
Net loss—diluted	$	(38,023	)	$	(36,676	)	$	(46,894	)
Denominator:
Weighted-average common shares outstanding—basic		15,688			12,156			10,010
Dilutive effect of warrants		—			—			242
Weighted-average common shares outstanding—diluted		15,688			12,156			10,252
Net loss per common share:
Basic	$	(2.42	)	$	(3.02	)	$	(4.30	)
Diluted	$	(2.42	)	$	(3.02	)	$	(4.57	)

The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands):

	As of December 31,
	2016		2015		2014
Warrants to purchase shares of common stock		218		938		1,496
Convertible preferred stock		4,270		3,353		—
Options to purchase shares of common stock		2,697		2,153		1,764
Outstanding securities not included in calculations		7,185		6,444		3,260