NET LOSS PER SHARE

12 Months Ended

Dec. 31, 2017

Basic net loss per share is calculated by dividing net loss by the weighted average number of shares outstanding for the period. Diluted net loss per share is calculated by dividing net loss by the weighted average number of common shares and potential dilutive common share equivalents outstanding during the period if the effect is dilutive. The Company’s potentially dilutive common shares include outstanding stock options and warrants and non-vested restricted stock units.

The following table presents the potential common shares outstanding that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti-dilutive (in thousands):



	Years Ended December 31,
	2017	2016	2015
Stock options to purchase common stock	8,433	8,981	8,646
Unvested restricted stock units	3,029	906	1,506
Warrants to purchase common stock	1,083	—	111
Total	12,545	9,887	10,263