Stock-based compensation (Tables)

6 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Nonvested Restricted Stock Units Activity

Activity with respect to the Company’s restricted stock units during the six months ended March 31, 2023 was as follows:

(in thousands, except per share data)	Shares	Weighted average grant date fair value per share
Nonvested shares at September 30, 2022	1,566	$	67.66
Granted	851	27.36
Vested/Issued	(290)	59.99
Forfeited	(290)	77.74
Nonvested shares at March 31, 2023	1,837	$	48.58

Schedule of Nonvested Performance-based Units Activity

Activity under the PSUs during the six months ended March 31, 2023 is summarized below:

(in thousands, except per share data)	Shares	Weighted average grant date fair value per share
Nonvested shares at September 30, 2022	529	$	79.60
Granted	480	28.14
Vested/Issued	(18)	51.08
Forfeited	(196)	84.83
Nonvested at March 31, 2023	795	$	47.87

Schedule of Activity Under Option and Performance Stock Options

Options activity during the six months ended March 31, 2023 is summarized below:

(in thousands, except per share data)	Shares	Weighted average exercise price per share		Weighted average remaining contractual term (years)	Aggregate intrinsic value
Outstanding at September 30, 2022	2,453	$	24.67	6.33	$	33,447
Granted	—	—		—	—
Forfeited	(71)	35.15		—	—
Exercised	(58)	14.86		—	639
Outstanding at March 31, 2023	2,324	$	24.59	5.78	$	4,250
Nonvested at March 31, 2023	290	36.46		6.74	100
Exercisable	2,034	$	22.90	5.65	$	4,150

Activity under the PSOs during the six months ended March 31, 2023 is summarized below:

(in thousands, except per share data)	Shares	Weighted average exercise price per share		Weighted average remaining contractual term (years)	Aggregate intrinsic value
Outstanding at September 30, 2022	312	$	61.35	8.33	$	296
Exercisable at September 30, 2022	19	$	31.29	9.57	$	74
Nonvested at September 30, 2022	293	63.27		8.25	222
Vested	(237)	$	70.84	—	$	—
Nonvested at March 31, 2023	56	$	31.29	9.07	$	—
Exercisable at March 31, 2023	256	67.95		7.56	—
Outstanding at March 31, 2023	312	$	61.35	7.83	$	—

Schedule of Stock-Based Compensation Expenses

Total stock-based compensation (credit)/expense recognized was as follows:

	Three months ended March 31,				Six months ended March 31,
(in thousands)	2023		2022		2023		2022
Cost of revenues	$	1,469	$	1,241	$	2,612	$	2,119
Research and development	3,090		4,838		7,508		8,865
Selling, general and administrative	5,700		16,258		(2,186)		29,421
Total stock-based compensation	$	10,259	$	22,337	$	7,934	$	40,405

Summary of Stock Option Valuation Assumptions

The number of shares reserved for issuance at March 31, 2023 was as follows:

(In thousands)	Shares available
Reserved at September 30, 2022	507
Additional shares authorized	249
Shares issued during the period	(132)
Reserved at March 31, 2023	624