Net Loss Per Share (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Net Loss Per Share

Basic and diluted net loss per share

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

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2020		2019		2020		2019
Numerator:
Net loss attributable to common stockholders ($in millions)	$	(30.9)	$	(31.1)	$	(88.4)	$	(75.8)
Denominator:
Weighted average common shares outstanding — basic and diluted		53,997,315		11,178,924		25,935,362		11,079,303
Net loss per share attributable to common stockholders — basic and diluted	$	(0.57)	$	(2.78)	$	(3.41)	$	(6.84)

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

	Year Ended December 31,
	2018		2019
Numerator:
Net loss attributable to common stockholders (in millions)	$	(52.9)	$	(108.5)
Denominator:
Weighted average common shares outstanding — basic and diluted		10,931,776		11,124,397
Net loss per share attributable to common stockholders — basic and diluted	$	(4.84)	$	(9.75)

Antidilutive potential common shares

computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:

	As of
	September 30,
	2020	2019
Options to purchase common stock	4,814,924	3,925,395
Convertible preferred stock (as converted to common stock)	—	31,557,107
	4,814,924	35,482,502

	December 31,
	2018	2019
Options to purchase common stock	2,169,000	4,048,802
Convertible preferred stock (as converted to common stock)	24,445,555	31,557,107
	26,614,555	35,605,909