16. Net loss per share

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company (in thousands, except per share data):

	December 31,
	2017			2016			2015
Net loss attributable to common stockholders- basic and diluted	$	(84,979	)	$	(95,817	)	$	(82,177	)
Net loss per share- basic and diluted	$	(2.41	)	$	(3.11	)	$	(2.84	)
Weighted-average common shares used to compute net loss per share- basic and diluted		35,228			30,784			28,964

Basic net loss attributable to common stockholders per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted net loss attributable to common stockholders per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period, determined using the treasury-stock method and the as-if converted method, for convertible securities, if inclusion of these is dilutive. Because the Company has reported a net loss for the years ended December 31, 2017 and 2016, diluted net loss per common share is the same as basic net loss per common share for those years.

The following potentially dilutive securities outstanding at the end of the years presented have been excluded from the computation of diluted shares outstanding:

	December 31,
	2017		2016		2015
Options to purchase common stock		3,645,456		4,452,700		3,240,969
Restricted stock units		2,518,740		502,027		254,067