14. Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:


	Years ended December 31,
	2019		2020
Numerator:
Net loss	$	(7,830)	$	(8,445)
Dividend on convertible exchangeable preferred shares		(201)		(201)
Beneficial conversion feature of Series B preferred stock		—		(3,775)
Conversion of Series B preferred stock		—		—
Net loss attributable to common shareholders	$	(8,031)	$	(12,421)
Denominator:
Weighted-average number of common shares used in loss per share – basic and diluted		816,080		3,633,385
Loss per share – basic and diluted	$	(9.84)	$	(3.42)

Potential dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, 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:


	December 31,	December 31,
	2019	2020
Stock options	100,278	602,683
6% convertible exchangeable preferred stock	85	85
Series A preferred stock	6,600	6,600
Series B preferred stock	—	1,188,725
Common stock warrants	374,525	4,143,379
Total shares excluded from calculation	481,488	5,941,472