Net Loss Per Share

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Net Loss Per Share

Net Loss Per Share

The Company applies the two-class method for calculating basic earnings per share. Under the two-class method, net income (loss) is reduced by cumulative preferred stock dividends and the residual amount is allocated between common stock and other participating securities based on their participation rights. Participating securities comprised of restricted common stock, which participate in dividends, if declared, by the Company. As the Company has reported a net loss for all periods, and the participating securities were not contractually obligated to share in the losses of the Company, accordingly, no losses were allocated to the participating securities.

Basic earnings per share is calculated by dividing net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding, net of the weighted average unvested restricted stock subject to repurchase by the Company, if any, during the period. Diluted earnings per share is calculated by dividing the net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding, adjusted for the effects of potentially dilutive common stock, which are comprised of stock options, restricted stock units and stock warrants, using the treasury-stock method, and convertible preferred stock, using the if-converted method. Because the Company reported losses attributable to common stockholders for all periods presented, all potentially dilutive common stock are antidilutive for those periods.

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders during the years ended December 31, 2016, 2015 and 2014 (in thousands, except per share data):

	Year Ended December 31,
	2016			2015			2014
Net loss	$	(41,708	)	$	(64,911	)	$	(48,429	)
Weighted-average common shares outstanding	84,483			81,914			70,837
Net loss per share — basic and diluted	$	(0.49	)	$	(0.79	)	$	(0.68	)

The following table presents the number of anti-dilutive shares excluded from the calculation of diluted net loss per share attributable to common stockholders at December 31, 2016, 2015 and 2014 (in thousands):

	December 31,
	2016	2015	2014
Options to purchase common stock	24,542	24,278	25,590
Common stock warrants	1,459	1,631	3,926
Unvested restricted stock awards	4,339	3,747	828
Total shares excluded from net loss per share attributable to common stockholders	30,340	29,656	30,344