16. Net Loss Per Share

Basic net loss per share is calculated based on the net loss attributable to common stockholders divided by the weighted average number of shares outstanding for the period. The calculation of diluted net loss per share excludes the potential conversion of all dilutive convertible securities, such as convertible debt and convertible preferred stock, and the potential exercise or vesting of other dilutive securities, such as options, warrants and restricted stock, as their inclusion would have an anti-dilutive effect. Accordingly, diluted net loss per share is the same as basic net loss per share.

The computation of net loss per share is as follows (in thousands, except per share amounts):



	Year Ended December 31,
	2018			2017
Net loss attributable to common stockholders	$	(29,400	)	$	(45,020	)
Basic and diluted:
Weighted average shares outstanding	56,106			36,569
Less: weighted average restricted shares outstanding	(33		)	(124		)
Shares used in calculation of basic and diluted net loss per common share	56,073			36,445
Net loss per common share: Basic and diluted	$	(0.52	)	$	(1.24	)

Common shares underlying equity awards, warrants, convertible preferred stock and other convertible securities aggregating 15.3 million shares and 5.2 million shares for the years ended December 31, 2018 and 2017, respectively, prior to the application of the treasury stock method, have been excluded from the calculation of diluted net loss per share because they were anti-dilutive.