Palo Alto Investors, LLC

Hedge Fund • Long/Short

Palo Alto Investors, LLC is a Long/Short Hedge Fund based in Palo Alto, CA led by Angela Elizabeth Nguyen-Dinh, reporting $667.0M in AUM as of Q3 2025 with 98% Healthcare concentration and 67% concentrated in top 10 holdings.

CCOAngela Elizabeth Nguyen-Dinh

Portfolio Value: $540.4M
Positions: 44
Top Holding: INSM at 13.11%
Last Reported: Q3 2025

Address101 University Ave, Suite 200, Palo Alto, CA, 94301-1638, United States

Top Holdings

Largest long holdings in Palo Alto Investors, LLC's portfolio (67.2% of total portfolio)

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Holding	Sector	Position	Weight	Traded	Ownership	Owned Since
1 Insmed INSM	Biotechnology Healthcare	$70.8M	13.11%	-$53.8M Sold	0.23% 491.8K shares	≤ Q2 2013 Held for 12y 5m+
2 PTC Therapeutics PTCT	Biotechnology Healthcare	$52.9M	9.80%	+$28.0M Bought	1.09% 862.6K shares	Q3 2024 Held for 1y 2m
3 Acadia Pharmaceuticals ACAD	Biotechnology Healthcare	$52.6M	9.74%	-$2.1M Sold	1.46% 2.5M shares	Q1 2016 Held for 9y 8m
4 Amicus Therapeutics FOLD	Biotechnology Healthcare	$42.3M	7.83%	-$1.9M Sold	1.74% 5.4M shares	≤ Q2 2013 Held for 12y 5m+
5 BioMarin Pharmaceuticals BMRN	Biotechnology Healthcare	$40.8M	7.56%	-$4.7M Sold	0.39% 754.0K shares	≤ Q2 2013 Held for 12y 5m+
6 Biogen BIIB	Drug Manufacturers - General Healthcare	$26.0M	4.81%	-$2.8M Sold	0.13% 185.7K shares	Q4 2020 Held for 4y 11m
7 United Therapeutics UTHR	Biotechnology Healthcare	$24.4M	4.51%	-$15.6M Sold	0.13% 58.2K shares	≤ Q2 2013 Held for 12y 5m+
8 AnaptysBio, Inc. ANAB	Biotechnology Healthcare	$20.6M	3.82%	-$4.3M Sold	2.41% 673.5K shares	Q3 2020 Held for 5y 2m
9 Iovance Biotherapeutics, Inc. IOVA	Biotechnology Healthcare	$16.5M	3.06%	+$9.1M Bought	2.11% 7.6M shares	Q4 2023 Held for 1y 11m
10 NovoCure NVCR	Medical - Instruments & Supplies Healthcare	$16.2M	3.00%	+$3.8M Bought	1.12% 1.3M shares	Q1 2023 Held for 2y 8m

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Changes

Portfolio activity, position movements, and quarter-over-quarter changes in Palo Alto Investors, LLC's latest filing

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Market Value

$540.4M

Prior: $469.9M

Q/Q Change

+14.99%

+$70.4M

Net Flows % of MV

-7.64%

Turnover Ratio

19.22%

New Purchases

3 stocks

$5.8M

Added To

13 stocks

+$77.4M

Sold Out Of

4 stocks

$15.3M

Reduced Holdings

19 stocks

-$109.3M

Increased Positions

Position	Shares Δ	Change
1 CareDx CDNA	New	0 → 316.2K +$4.6M
2 Oruka Therapeutics, Inc. ORKA	New	0 → 60.0K +$791.3K
3 ProQR Therapeutics PRQR	New	0 → 188.8K +$402.2K
4 Ultragenyx Pharmaceutical RARE	+658.01%	48.8K → 369.5K +$9.6M
5 Dyne Therapeutics, Inc. DYN	+376.52%	265.0K → 1.3M +$12.6M

Decreased Positions

Position	Shares Δ	Change
1 Staar Surgical STAA	Sold	791.9K → 0 −$13.3M
2 Karyopharm Therapeutics KPTI	Sold	187.9K → 0 −$809.9K
3 Vyne Therapeutics VYNE	Sold	445.4K → 0 −$735.0K
4 Alumis Inc. ALMS	Sold	143.4K → 0 −$430.3K
5 Alnylam Pharmaceuticals ALNY	-57.21%	75.5K → 32.3K −$19.7M