10. Net Loss per Share

Diluted loss per share is the same as basic loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive, given the Company's net loss. The following securities have been excluded from the calculation of weighted-average shares of common stock outstanding because the effect is anti-dilutive for the years ended December 31, 2015, 2014 and 2013:

	Year Ended December 31,
	2015		2014		2013
Redeemable convertible preferred stock:
Series A		—		—		10,033,976
Series B		—		—		5,057,901
Series C		—		—		4,429,601
Series D		—		—		3,979,730
Warrants to purchase Series D redeemable convertible preferred stock		—		—		83,818
Stock options		5,298,510		5,850,211		5,883,885
Restricted stock units		1,220,008		992,665		—

Basic and diluted net loss per share attributable to holders of common stock is calculated as follows:

	Year Ended December 31,
	2015			2014			2013
Numerator (in thousands):
Net loss attributable to holders of common stock	$	(26,733	)	$	(29,088	)	$	(28,300	)


Denominator:
Weighted-average shares of common stock outstanding, basic and diluted		42,420,356			32,075,107			7,432,055


Net loss per share attributable to holders of common stock, basic and diluted	$	(0.63	)	$	(0.91	)	$	(3.81	)