Net Loss Per Share (Tables)

6 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table presents the computation of basic and diluted net loss per share for the three and six months ended March 31, 2024 and 2023.

	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
	(in thousands, except per share amounts)
Numerator:
Net (loss) income attributable to Arrowhead Pharmaceuticals, Inc.	$	(125,300)	$	48,675	$	(258,164)	$	7,350
Denominator:
Weighted-average basic shares outstanding	123,285		106,757		115,307		106,394
Effect of dilutive securities	—		1,386		—		1,499
Weighted-average diluted shares outstanding	123,285		108,143		115,307		107,893
Basic net (loss) gain per share	$	(1.02)	$	0.46	$	(2.24)	$	0.07
Diluted net (loss) gain per share	$	(1.02)	$	0.45	$	(2.24)	$	0.07

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive.

	Three Months Ended March 31,		Six Months Ended March 31,
	2024	2023	2024	2023
	(in thousands)
Options	595	767	657	779
Restricted stock units	3,411	3,583	3,931	3,290
Total	4,006	4,350	4,588	4,069