14. 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. Prior to the Company’s IPO of its common stock, the Company’s convertible preferred stock was entitled to receive dividends, prior and in preference to any declaration or payment of any dividend on common stock and thereafter participate pro rata on an as converted basis with the common stock holders on any distributions to common stockholders. The convertible preferred shares were therefore considered to be participating securities. As a result, the Company calculated the net loss per share using the two-class method. Accordingly, the net loss attributable to common stockholders is derived from the net loss for the period and, in periods in which the Company has net income attributable to common stockholders, an adjustment is made for the noncumulative dividends and allocations of earnings to participating securities based on their outstanding shareholder rights. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible preferred stock as the convertible preferred stock did not have a contractual obligation to share in the Company’s losses. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods when the Company has incurred a net loss, convertible preferred stock, options to purchase common stock, common stock warrants and common stock subject to repurchase are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive.

The following table provides the basic and diluted net loss per common share computations for the years ended December 31, 2016, 2015 and 2014.


	Year ended December 31,
(in thousands, except per share data)	2016		2015		2014

Basic and diluted loss per share:
Net loss	$	(95,765)	$	(70,275)	$	(5,152)

Weighted-average common shares outstanding		51,667		27,687		6,670
Less: weighted-average unvested common shares subject to repurchase		(91)		(1,483)		(1,870)
Weighted-average number of shares used in computing net loss per share, basic and diluted		51,576		26,204		4,800

Basic and diluted net loss per share	$	(1.86)	$	(2.68)	$	(1.07)

Potentially dilutive shares that were not included in the diluted per share calculations because they would be antidilutive as of the years ended December 31, 2016, 2015 and 2014 were as follows:


	Year ended December 31,
	2016	2015	2014

Options to purchase common stock	9,043	9,316	8,450
Warrants to purchase common stock	377	377	864
Restricted stock units	159	—	—
Employee stock purchase plan	90	—	—
Common stock subject to repurchase	—	1,307	1,690
Convertible preferred stock	—	—	31,397
	9,669	11,000	42,401