12. 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 common shares outstanding because the effect is anti-dilutive:

	Three and Six Months Ended June 30,
	2013	2014
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	12,797	—
Stock options	5,604,989	6,388,908
Restricted stock units	—	1,001,390

Basic and diluted net loss per share attributable to common stockholders is calculated as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
	2013			2014			2013			2014
Numerator (in thousands):
Net loss attributable to common stockholders	$	(8,982	)	$	(10,597	)	$	(12,815	)	$	(17,734	)
Denominator:
Weighted-average common shares outstanding, basic and diluted	7,398,059			39,304,884			7,392,129			23,588,330
Net loss per share attributable to common stockholders, basic and diluted	$	(1.21	)	$	(0.27	)	$	(1.73	)	$	(0.75	)