14. Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows for the years ended December 31, 2019, 2018 and 2017:


	Year Ended December 31,
	2019		2018		2017
Numerator:
Net loss attributable to common stockholders	$	(86,372)	$	(59,978)	$	(63,386)
Denominator:
Weighted average common shares outstanding, basic and diluted		45,273,231		38,115,142		28,818,196
Net loss per share attributable to common stockholders, basic and diluted	$	(1.91)	$	(1.57)		(2.20)

The Company excluded the following common stock equivalents, outstanding as of December 31, 2019, 2018, and 2017, from the computation of diluted net loss per share attributable to common stockholders for the years ended December 31, 2019, 2018 and 2017 because they had an anti-dilutive impact due to the net loss incurred for the periods. The Company also excluded the shares issuable upon conversion of the 2026 Convertible notes from the computation of diluted net loss per share for the year ended December 31, 2019 because they had an anti-dilutive impact.


	December 31,
	2019	2018	2017
Options to purchase common stock	7,920,417	5,230,831	4,002,374
Shares issuable upon conversion of 2026 Convertible Notes, if converted	5,769,232	—	—
Warrants for the purchase of common stock	18,939	18,939	18,939
	13,708,588	5,249,770	4,021,313