Stock option plan (Tables)

12 Months Ended

Sep. 30, 2020

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity

The number of shares reserved for issuance as at September 30, 2020 is as follows:

(In thousands)	Shares available
Outstanding at September 30, 2019		56
Additional shares authorized		249
Shares issued during the period		(126	)
Outstanding at September 30, 2020		179

Activity Under The Equity Incentive Plans

Activity under the equity incentive plans during the year ended September 30, 2020 is as follows:

(In thousands, except per share data)	Shares available			Options outstanding			Weighted average exercise price per share		Weighted average remaining contractual term (years)		Aggregate intrinsic value
Outstanding at September 30, 2019		1,521			3,550		$	15.99		8.3	$	31,998
Additional shares authorized		1,000			—			—
Stock options granted		(1,481	)		1,481			35.49
Stock options exercised		—			(915	)		11.50
Stock options forfeited		203			(203	)		23.39
Restricted stock units granted		(312	)		—			—
Early exercised options repurchased		2			—			—
Forfeiture of restricted stock units		30			—			—
Shares withheld for payment of taxes		71			—			—
Outstanding at September 30, 2020		1,034			3,913		$	24.35		8.1	$	204,365
Vested or expected to vest at September 30, 2020					3,913		$	24.35		8.1	$	204,365
Vested and exercisable at September 30, 2020					1,312		$	14.26		7.0	$	80,995

Schedule of Nonvested Restricted Stock Units Activity

Activity with respect to the Company’s restricted stock units during the year ended September 30, 2020 is as follows:

(in thousands, except per share data)	Number of Shares			Weighted average grant date fair value per share		Weighted average remaining contractual term (years)		Aggregate Intrinsic Value
Outstanding at September 30, 2019		462		$	26.16		3.9	$	8,959
Restricted stock units granted		312			38.66		—		—
Restricted stock units vested		(175	)		26.36		—		—
Restricted stock units forfeited		(30	)		26.12		—		—
Outstanding at September 30, 2020		569		$	32.96		3.2	$	43,260
Expected to vest at September 30, 2020		569		$	32.96		3.2	$	43,260

Total Stock-based Compensation Expense

Total stock-based compensation expense recognized were as follows:

	Year ended September 30,
(in thousands)	2020		2019		2018
Cost of revenues	$	1,290	$	1,345	$	376
Research and development		3,346		2,378		705
Selling, general and administrative		12,460		7,447		1,880
Total stock-based compensation	$	17,096	$	11,170	$	2,961

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value of options granted during the years ended September 30, 2020, 2019 and 2018, respectively, were calculated using the weighted average assumptions set forth below:

	Year ended September 30,
	2020			2019			2018
Expected term (years)		6.2			6.4			6.3
Expected volatility		62.1	%		60.2	%		66.3	%
Risk-free interest rate		1.3	%		2.7	%		2.7	%
Dividend yield		0	%		0	%		0	%