9. Net Loss Per Common Share

Net Loss Per Common Share

Basic net loss per common share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per common share is computed using the sum of the weighted average number of common shares outstanding during the period and, if dilutive, the weighted average number of potential shares of common stock, including the assumed exercise of stock options, stock warrants and unvested restricted common stock. The Company applies the two-class method to calculate its basic and diluted net loss per share attributable to common stockholders, as its preferred stock and common stock are participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. However, the two-class method does not impact the net loss per share of common stock as the Company was in a net loss position for each of the periods presented and preferred stockholders do not participate in losses. For the years ended December 31, 2017, 2016 and 2015, the following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding because the effect would be anti-dilutive (in thousands):


	Year Ended	Year Ended	Year Ended
	December 31,	December 31,	December 31,
	2017	2016	2015
Stock options	3,167	2,577	1,749
Stock warrants	306	306	326
Unvested service-based restricted stock units	27	58	—
Unvested performance-based restricted stock units	49	—	1,751
	3,549	2,941	3,826

Amounts in the table above reflect the common stock equivalents of the noted instruments.

The following table summarizes the calculation of the basic and diluted net loss per common share (in thousands, except per share data):


	Year Ended		Year Ended		Year Ended
	December 31,		December 31,		December 31,
	2017		2016		2015
Numerator:
Net loss and comprehensive loss	$	(218,051)	$	(83,012)	$	(38,474)
Denominator:
Weighted-average basic and diluted common shares		29,935		22,648		7,088
Basic and diluted net loss per common share	$	(7.28)	$	(3.67)	$	(5.43)