13. Net Loss per Share

Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period.

In periods when the Company has incurred a net loss, common stock equivalents such as outstanding common stock options, restricted stock units, unvested common shares subject to repurchase and warrants are excluded from the calculation of diluted net loss per share as they give an anti-dilutive effect.

For the year ended December 31, 2017, the Company reversed $1.1 million of remeasurement gain on the change in the fair value of warrants from its net loss and included the incremental shares from the assumed exercise of the warrants in the computation of its weighted-average shares outstanding as they yielded a dilutive effect to the net loss per share in the period. Other potentially dilutive common stock equivalents such as outstanding common stock options, shares to be purchased under the employee stock purchase plan, and restricted stock units were excluded as their effect was anti-dilutive and the net loss per share would be reduced.

The following table provides the basic and diluted net loss per share computations for the years ended December 31, 2018, 2017 and 2016:


	Year ended December 31,
(in thousands, except per share data)	2018		2017		2016
			(As Revised)		(As Revised)
Numerator:
Net loss used to compute net loss per share, basic	$	(128,154)	$	(137,628)	$	(100,327)

Less: Remeasurement gain on warrant liability		—		(1,148)		—
Net loss used to compute net loss per share, diluted	$	(128,154)	$	(138,776)	$	(100,327)

Denominator:
Weighted-average common shares outstanding		57,848		53,312		51,667
Less: Weighted-average unvested common shares subject to repurchase		—		—		(91)
Weighted-average number of shares used in computing net loss per share, basic		57,848		53,312		51,576

Add: Incremental shares from assumed exercise of warrants		—		292		—
Weighted-average number of shares used in computing net loss per share, diluted		57,848		53,604		51,576

Net loss per share, basic	$	(2.22)	$	(2.58)	$	(1.95)
Net loss per share, diluted	$	(2.22)	$	(2.59)	$	(1.95)

The following table shows the potentially dilutive common stock equivalents that were excluded from the computations of diluted net loss per share as their effect would be anti-dilutive, as of December 31, 2018, 2017 and 2016:


	As of December 31,
	2018	2017	2016

Options to purchase common stock	9,463	9,963	9,043
Warrants to purchase common stock	—	—	377
Restricted stock units	1,084	389	159
Employee stock purchase plan	42	79	90
	10,589	10,431	9,669