9. Net Loss Per Share

Basic and diluted net loss per share for the three and nine months ended September 30, 2020 and 2019 was calculated as follows (in thousands except share and per share amounts).


	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Numerator:
Net loss	$	(7,057)	$	(7,935)	$	(20,804)	$	(24,904)
Dividend attributable to down round feature of warrants		—		—		(303)		(359)
Dividend attributable to Series A & B convertible preferred stock		—		—		(372)		—
Series A & B convertible preferred stock - beneficial conversion feature		—		—		(9,399)		—
Net loss attributable to common stockholders for basic and diluted loss per share	$	(7,057)	$	(7,935)	$	(30,878)	$	(25,263)

Denominator:
Weighted average number of common shares outstanding – basic and diluted		76,321,644		23,923,196		53,548,902		22,039,386

Net loss per share attributable to common stockholders – basic and diluted	$	(0.09)	$	(0.33)	$	(0.58)	$	(1.15)

Included within weighted average common shares outstanding are 16,663,902 common shares issuable upon the exercise of the pre-funded warrants as the warrants are exercisable at any time for nominal consideration, and as such, the shares are considered outstanding for the purpose of calculating basic and diluted net loss per share attributable to common stockholders.

The Company’s potentially dilutive securities include RSUs, stock options and warrants. These securities were excluded from the computations of diluted net loss per share for the three and nine months ended September 30, 2020 and 2019, as the effect would be to reduce the net loss per share. The following table includes the potential shares of common stock, presented based on amounts outstanding at each period end, that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2020	2019	2020	2019
Restricted stock units to purchase common stock	753,106	—	753,106	—
Options to purchase common stock	6,278,853	4,019,566	6,278,853	4,019,566
Warrants to purchase common stock	36,040,833	10,369,752	36,040,833	10,369,752
	43,072,792	14,389,318	43,072,792	14,389,318