9.	Net Loss Per Share

Basic and diluted net loss per share was calculated as follows for the three and nine months ended September 30, 2018 and 2017:

	Three months ended September 30,						Nine months ended September 30,
	2018			2017			2018			2017
Basic net loss per share:
Numerator:
Net loss (in thousands)	$	(122,918	)	$	(73,719	)	$	(214,494	)	$	(200,698	)
Denominator:
Weighted average common stock outstanding —basic		46,706,770			37,470,912			45,866,676			37,367,802
Dilutive effect of shares of common stock equivalents resulting from common stock options and restricted stock units		—			—			—			—
Weighted average common stock outstanding —diluted		46,706,770			37,470,912			45,866,676			37,367,802
Net loss per share—basic and diluted	$	(2.63	)	$	(1.97	)	$	(4.68	)	$	(5.37	)

The following common stock equivalents outstanding as of September 30, 2018 and 2017 were excluded from the computation of diluted net loss per share for the periods presented because including them would have been anti-dilutive:

	Three months ended September 30,				Nine months ended September 30,
	2018		2017		2018		2017
Stock options		6,396,175		5,259,925		6,396,175		5,259,925
Restricted stock units		13,800		30,100		13,800		30,100
Employee stock purchase plan		6,481		6,500		6,481		6,500
		6,416,456		5,296,525		6,416,456		5,296,525

Stock options and restricted stock units that are outstanding and contain performance-based vesting criteria for which the performance conditions have not been met are excluded from the calculation of common stock equivalents outstanding.