Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock-Based Compensation Expense by Award Type

Stock-based compensation expense recognized by award type is as follows (in thousands):

	Year ended December 31,
	2023		2022
			(As Restated)
Stock options	$	6,478	$	14,168
Restricted stock units	12,619		20,138
Employee stock purchase plan and other	332		784
	$	19,429	$	35,090

Schedule of Stock-Based Compensation Expense by Classification

Stock-based compensation expense by classification included within the consolidated statements of operations and comprehensive loss was as follows (in thousands):

	Year ended December 31,
	2023		2022
			(As Restated)
Cost of product revenue	$	881	$	—
Selling, general and administrative	9,548		15,831
Research and development	9,000		19,259
	$	19,429	$	35,090

Assumptions Used for the Black-Scholes Option-Pricing Model to Determine the Per Share Weighted Average Fair Value for Options Granted

The fair value of each option issued to employees was estimated at the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

	Year ended December 31,
	2023		2022
Expected volatility	70.9	%	66.4	%
Expected term (in years)	6.10		6.0
Risk-free interest rate	4.1	%	1.9	%
Expected dividend yield	0.0	%	0.0	%

Summary of Stock Option Activity Under Plan

The following table summarizes the stock option activity under the Company’s equity awards plans excluding awards held by employees of 2seventy bio:

	Shares (in thousands)	Weighted- average exercise price per share		Weighted- average contractual life (in years)	Aggregate intrinsic value (a) (in thousands)
Outstanding at December 31, 2022	2,668	$	24.38
Granted	2,077	$	4.89
Exercised	(3)	$	2.74
Canceled or forfeited	(515)	$	29.55
Outstanding at December 31, 2023	4,227	$	14.16	8.06	$	—
Exercisable at December 31, 2023	1,469	$	28.80	6.54	$	—
Vested and expected to vest at December 31, 2023	4,227	$	14.16	8.06	$	—

(a)The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that were in the money at December 31, 2023.

Summary of Restricted Common Stock Awards

The following table summarizes the restricted stock unit activity under the Company’s equity award plans excluding awards held by employees of 2seventy bio:

	Shares (in thousands)	Weighted-average grant date fair value
Unvested balance at December 31, 2022	2,415	$	11.44
Granted	3,369	4.76
Vested	(1,057)	14.35
Forfeited	(520)	8.09
Unvested balance at December 31, 2023	4,207	$	6.08