12. Net Loss Per Share

The Company calculates basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for companies with participating securities. The Company considered all series of redeemable convertible preferred stock to have been participating securities as the holders were entitled to receive non-cumulative dividends on a pari passu basis in the event a dividend was paid on common stock. Under the two-class method, the net loss attributable to common stockholders is not allocated to the redeemable convertible preferred stock as the holders of redeemable convertible preferred stock do not have a contractual obligation to share in losses.

Under the two-class method, basic net loss per share attributable to common stockholders is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase. Diluted net loss per share attributable to common stockholders is computed by giving effect to all potentially dilutive common stock equivalents outstanding for the period. For purposes of this calculation, redeemable convertible preferred stock, stock options to purchase common stock, early exercised stock options, and warrants to purchase redeemable convertible preferred stock and common stock are considered common shares equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive. Basic and diluted net loss per share was the same for each period presented, as the inclusion of all potential common shares outstanding would have been antidilutive.

The rights, including the liquidation and dividend rights, of the holders of Class A and Class B common stock are identical, except with respect to voting. As the liquidation and dividend rights are identical, the undistributed earnings are allocated on a proportionate basis and the resulting net loss per share attributed to common stockholders will, therefore, be the same for both Class A and Class B common stock on an individual or combined basis.

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data):


	Year Ended December 31,
	2019		2018
Numerator:
Net loss attributable to common stockholders for earnings per share, basic and diluted	$	67,484	$	37,940
Denominator:
Shares used to compute net loss per share, basic and diluted		15,834,175		2,104,861

Basic and diluted net loss attributable to common stockholders per share	$	4.26	$	18.02

The following outstanding potentially dilutive common shares were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because the impact of including them would have been antidilutive:


	Year Ended December 31,
	2019		2018
Convertible preferred stock (as converted)		—		17,248,259
Common stock options		3,742,144		2,136,291
Common stock warrants		49,997		62,936
Convertible preferred stock warrants		—		49,997
Early exercised stock options		913		—
		3,793,054		19,497,483