The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company:


	Year ended December 31,
(in thousands, except share and per share amounts)	2021			2020			2019
Numerator:
Net loss attributable to common stockholders	$	(120,314	)	$	(45,704	)	$	(19,297	)
Denominator:
Weighted average number of common shares, basic and diluted		26,872,036			2,250,093			1,277,156
Net loss per common share attributable to common stockholders, basic and diluted	$	(4.48	)	$	(20.31	)	$	(15.11	)

The Company’s potential dilutive securities, which include convertible preferred stock, unvested restricted stock and common stock options, have been excluded from the computation of diluted net loss per share as the effects would be anti-dilutive. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at period end, from the computation of diluted net loss per share attributable to common stockholders for the period indicated because including them would have had an anti-dilutive effect:


	Year ended December 31,
	2021		2020		2019
Convertible preferred stock		—		19,387,544		5,553,367
Unvested restricted stock		—		537,633		1,075,268
Unvested restricted stock units		32,000		—		—
Outstanding options to purchase common stock		6,119,295		3,888,823		1,933,507
Total		6,151,295		23,814,000		8,562,142

As part of the license agreements with Harvard and Broad, the Company is required to make success payments. The Company may elect to make these payments by issuing shares of the Company's common stock. As of December 31, 2021, an aggregate of $6.3 million was earned relating to these success payments, which the Company settled in cash in November 2021.