Palo Alto Investors LP

CIK

1306923

City

PALO ALTO

State / Country

Stock

PRTA — Prothena Corp Public Ltd Co

Top Portfolio Positions

51 positions · $653,863,072 total · as of Mar 31, 2026

Ticker	Company	Shares	Value (USD)	% of Portfolio
INSM	INSMED Inc Healthcare	415,269	$67,904,786	10.39%
ACAD	Acadia Pharmaceuticals Inc Healthcare	2,872,695	$63,946,190	9.78%
PTCT	Ptc Therapeutics, Inc. Healthcare	921,607	$62,789,084	9.60%
BMRN	Biomarin Pharmaceutical Inc Healthcare	685,182	$38,705,931	5.92%
UTHR	UNITED THERAPEUTICS Corp Healthcare	62,809	$37,244,480	5.70%
ANAB	Anaptysbio, Inc Healthcare	638,161	$35,392,409	5.41%
MIRM	Mirum Pharmaceuticals, Inc. Healthcare	325,175	$30,039,666	4.59%
DYN	Dyne Therapeutics, Inc. Healthcare	1,652,972	$29,968,382	4.58%
BIIB	Biogen Inc. Healthcare	140,719	$25,798,014	3.95%
IRON	Disc Medicine, Inc. Healthcare	401,719	$25,685,912	3.93%

25 quarters · across all stocks

25 quarters on record

Report Date	Value (USD)	Shares	Change	Type	Discretion	Filed
2026-03-31	$11,747,280	1,208,568	-8.5%	Shares	Sole	2026-05-15
2025-12-31	$12,610,870	1,320,510	-0.3%	Shares	Sole	2026-02-17
2025-09-30	$12,922,513	1,324,028	+3.9%	Shares	Sole	2025-11-14
2025-06-30	$7,737,750	1,274,753	-23.2%	Shares	Sole	2025-08-14
2025-03-31	$20,539,208	1,659,734	-4.5%	Shares	Sole	2025-05-15
2024-12-31	$24,070,801	1,737,964	0.0%	Shares	Sole	2025-02-14
2024-09-30	$29,076,137	1,737,964	+4.3%	Shares	Sole	2024-11-14
2024-06-30	$34,394,041	1,666,378	+0.2%	Shares	Sole	2024-08-14
2024-03-31	$41,203,606	1,663,448	+0.2%	Shares	Sole	2024-05-15
2023-12-31	$60,326,471	1,660,057	+0.2%	Shares	Sole	2024-02-15
2023-09-30	$79,972,348	1,657,458	0.0%	Shares	Sole	2023-11-14
2023-06-30	$113,171,232	1,657,458	-0.4%	Shares	Sole	2023-08-14
2023-03-31	$80,643,271	1,663,777	+0.3%	Shares	Sole	2023-05-15
2022-12-31	$99,929,264	1,658,577	+0.5%	Shares	Sole	2023-02-14
2022-09-30	$100,025,979	1,649,777	-1.9%	Shares	Sole	2022-11-14
2022-06-30	$45,652,100	1,681,477	0.0%	Shares	Sole	2022-08-15
2022-03-31	$61,491,613	1,681,477	-0.2%	Shares	Sole	2022-05-16
2021-12-31	$83,252,930	1,685,282	0.0%	Shares	Sole	2022-02-14
2021-09-30	$120,042,636	1,685,282	-2.7%	Shares	Sole	2021-11-15
2021-06-30	$89,015,489	1,731,482	-0.6%	Shares	Sole	2021-08-16
2021-03-31	$43,771,725	1,742,505	+3.0%	Shares	Sole	2021-05-17
2020-12-31	$20,318,578	1,691,805	+27.3%	Shares	Sole	2021-02-16
2020-09-30	$13,274,052	1,328,734	+72.3%	Shares	Sole	2020-11-16
2020-06-30	$8,065,339	771,065	-0.5%	Shares	Sole	2020-08-14
2020-03-31	$8,295,667	775,296	—	Shares	Sole	2020-05-15
No 13F history on record for this holder in this stock.