Q1 2026 13F · SEC CIK 1306923

Palo Alto Investors LP

Hedge fundFiled 2026-05-15 for Q1 2026. Open the filing ↗ · All SEC filings ↗

Reported 13F value: $653.9M
Reported positions: 51
Top holdings a year, 3 yrs: +10.6%
Assets under management: $696.0M

Palo Alto Investors LP is a hedge fund that reported 51 positions worth $653.9M in its Q1 2026 13F, filed 2026-05-15. Its largest holdings were Insmed Inc (INSM, 10.4%), Acadia Pharmaceuticals Inc (ACAD, 9.8%), Ptc Therapeutics Inc (PTCT, 9.6%). A portfolio copying its top holdings returned 10.6% a year over the last 3 years, against 20.4% for the S&P 500.

Palo Alto Investors LP holdings largest 50 of 51 positions.

Weights are shares of the filer's total reported 13F value, compared with Q4 2025. Share changes may reflect splits; weight changes also reflect price moves. A 13F shows long US-listed positions only, up to 135 days after the fact.

Palo Alto Investors LP 13F holdings
Stock	% of 13F value	Q4 2025	Shares	Share change	Reported value
INSMInsmed Inc	10.4%	11.9%	415,269	-15.2%	$67.9M
ACADAcadia Pharmaceuticals Inc	9.8%	9.2%	2,872,695	+15.6%	$63.9M
PTCTPtc Therapeutics Inc	9.6%	9.6%	921,607	+2.0%	$62.8M
BMRNBiomarin Pharmaceutical Inc	5.9%	6.2%	685,182	-8.2%	$38.7M
UTHRUnited Therapeutics Corp	5.7%	3.9%	62,809	+7.9%	$37.2M
ANABAnaptysbio Inc	5.4%	4.7%	638,161	-7.5%	$35.4M
MIRMMirum Pharmaceuticals Inc	4.6%	1.7%	325,175	+107.9%	$30.0M
DYNDyne Therapeutics Inc	4.6%	4.0%	1,652,972	+12.3%	$30.0M
BIIBBiogen Inc	3.9%	4.5%	140,719	-23.3%	$25.8M
IRONDisc Medicine Inc	3.9%	3.5%	401,719	+26.5%	$25.7M
IOVAIovance Biotherapeutics Inc	3.4%	2.7%	6,349,563	-10.8%	$22.3M
SNDXSyndax Pharmaceuticals Inc	3.1%	2.3%	864,986	+8.9%	$20.2M
ANNXAnnexon Inc	2.5%	1.7%	2,948,090	+23.7%	$16.3M
FOLDAmicus Therapeutic	2.5%	10.3%	1,113,045	-78.6%	$16.1M
NVCRNovocure Ltd	2.1%	2.3%	1,280,439	-1.4%	$14.0M
RAREUltragenyx Pharmaceutical in	1.9%	1.5%	596,495	+29.3%	$12.5M
PRTAProthena Corp PLC	1.8%	1.8%	1,208,568	-8.5%	$11.7M
BCAXBicara Therapeutics Inc	1.7%	0.7%	550,408	+84.3%	$10.9M
CLDXCelldex Therapeutics Inc New	1.4%	New	296,408	—	$9.4M
CDNACaredx Inc	1.4%	1.3%	531,870	+11.2%	$9.2M
ALKSAlkermes PLC	1.3%	0.9%	242,560	+0.0%	$8.6M
CMPXCompass Therapeutics Inc	1.2%	1.9%	1,514,504	-40.2%	$8.0M
AGIOAgios Pharmaceuticals Inc	1.1%	0.8%	213,601	+0.5%	$7.2M
ALGNAlign Technology Inc	1.1%	0.9%	41,520	+0.0%	$7.1M
CAPRCapricor Therapeutics Inc	1.1%	0.9%	229,763	+1.5%	$7.0M
TVTXTravere Therapeutics Inc	1.0%	0.6%	230,453	+108.1%	$6.8M
TSHATaysha Gene Therapies Inc	1.0%	0.9%	1,391,382	+17.6%	$6.2M
ACRSAclaris Therapeutics Inc	0.9%	0.7%	1,613,430	+3.0%	$6.1M
DNLIDenali Therapeutics Inc Com	0.7%	1.5%	234,582	-63.4%	$4.5M
XENEXenon Pharmaceuticals Inc	0.5%	0.6%	51,345	-46.8%	$3.0M
ORKAOruka Therapeutics Inc	0.5%	0.3%	59,985	+0.0%	$2.9M
STOKStoke Therapeutics Inc	0.4%	0.3%	84,631	+17.5%	$2.8M
EWEdwards Lifesciences Corp	0.4%	0.4%	33,640	+0.0%	$2.7M
NBIXNeurocrine Biosciences Inc	0.4%	0.4%	18,117	+0.0%	$2.4M
NUVBNuvation Bio Inc	0.3%	0.7%	508,846	-5.4%	$2.2M
CYTKCytokinetics Inc	0.3%	New	32,195	—	$2.1M
EHTHEhealth Inc	0.3%	1.0%	1,482,797	-3.2%	$1.9M
CRSPCRISPR Therapeutics AG	0.3%	0.3%	39,605	-3.9%	$1.9M
BNTXBiontech SE	0.3%	0.3%	19,614	+0.0%	$1.7M
PYXSPyxis Oncology Inc	0.2%	0.2%	1,010,510	-2.6%	$1.5M
VSTMVerastem Inc	0.2%	New	246,093	—	$1.3M
BCYCBicycle Therapeutics PLC	0.1%	0.2%	201,890	-8.7%	$937K
MDGLMadrigal Pharmaceuticals Inc	0.1%	New	1,787	—	$935K
HUMHumana Inc	0.1%	0.1%	3,985	+0.0%	$691K
CMPSCompass Pathways PLC	0.1%	0.1%	115,616	+0.0%	$639K
XERSXeris Biopharma Holdings Inc	0.1%	New	104,410	—	$606K
ABEOAbeona Therapeutics Inc	0.1%	0.1%	108,865	+0.0%	$488K
INSPInspire Med Sys Inc	0.1%	0.1%	8,772	+0.0%	$452K
URGNUrogen Pharma Ltd	0.1%	0.1%	24,500	+0.0%	$441K
PRQRProqr Thrapeutics N V	0.0%	0.1%	188,807	+0.0%	$306K

What Palo Alto Investors LP bought and sold in Q1 2026, against Q4 2025.

Left the top 50

Share counts compared with the Q4 2025 13F; a split also changes share counts. The latest filing lists more than 50 positions, so a position that left the top 50 may still be held.

How the holdings did against the S&P 500.

1 year: +46.4% /yr; S&P 500 +20.1%
3 years: +10.6% /yr; S&P 500 +20.4%
5 years: +4.0% /yr; S&P 500 +11.6%

A portfolio of the filer's 20 largest 13F positions, weighted by value and rebuilt each quarter on the day the filing became public. 13Fs show long US-listed positions only, so this is an estimate of the stock picks, not the fund's reported returns.

Reported 13F value by quarter.

13F value by quarter
Quarter	13F value	Positions
Q1 2026	$653.9M	51
Q4 2025	$718.4M	49
Q3 2025	$540.4M	44
Q2 2025	$470.0M	45
Q1 2025	$525.1M	44
Q4 2024	$645.4M	43
Q3 2024	$769.9M	45
Q2 2024	$863.0M	39
Q1 2024	$886.7M	38
Q4 2023	$1.1B	34
Q3 2023	$1.1B	29
Q2 2023	$1.2B	30

Questions about Palo Alto Investors LP's portfolio

What stocks does Palo Alto Investors LP own?

Palo Alto Investors LP's latest 13F, for Q1 2026 and filed May 15, 2026, lists 51 positions worth $653.9M. The largest are Insmed Inc (INSM) at 10.4%, Acadia Pharmaceuticals Inc (ACAD) at 9.8%, Ptc Therapeutics Inc (PTCT) at 9.6%, Biomarin Pharmaceutical Inc (BMRN) at 5.9% and United Therapeutics Corp (UTHR) at 5.7%.

What did Palo Alto Investors LP buy last quarter?

In Q1 2026, Palo Alto Investors LP added a new position in Celldex Therapeutics Inc New (CLDX), a new position in Cytokinetics Inc (CYTK), a new position in Verastem Inc (VSTM), a new position in Madrigal Pharmaceuticals Inc (MDGL), a new position in Xeris Biopharma Holdings Inc (XERS), Travere Therapeutics Inc (TVTX) (+108.1% shares), Mirum Pharmaceuticals Inc (MIRM) (+107.9% shares) and Bicara Therapeutics Inc (BCAX) (+84.3% shares), compared with its Q4 2025 filing.

What did Palo Alto Investors LP sell last quarter?

In Q1 2026, Palo Alto Investors LP cut from its top 50 Gossamer Bio Inc (GOSS), cut from its top 50 Aldeyra Therapeutics Inc (ALDX), cut from its top 50 Generation Bio Co (GBIO), cut from its top 50 Akari Therapeutics Plc-Adr (AKTX), Amicus Therapeutic (FOLD) (-78.6% shares), Denali Therapeutics Inc Com (DNLI) (-63.4% shares) and Xenon Pharmaceuticals Inc (XENE) (-46.8% shares), compared with its Q4 2025 filing.

How has Palo Alto Investors LP's portfolio performed?

A portfolio copying Palo Alto Investors LP's 20 largest 13F holdings each quarter, from the day each filing was public, returned +10.6% a year over the last 3 years, against +20.4% for the S&P 500. Over 1 year: +46.4% against +20.1%. Over 5 years: +4.0% a year against +11.6%.

When is Palo Alto Investors LP's next 13F filing due?

13F filings are due 45 days after each quarter ends. Palo Alto Investors LP's filing for the quarter ending Jun 30, 2026 was due by Aug 14, 2026; this page updates once it is processed.

How much money does Palo Alto Investors LP manage?

Palo Alto Investors LP reported $696.0M of regulatory assets under management on its latest SEC Form ADV. Its 13F, which covers only US-listed stocks and options, totals $653.9M.