Palo Alto Investors LP — 13F Holdings & Portfolio
CIK 1306923 · latest 13F-HR filed 2026-05-15
Palo Alto Investors LP manages $653.9M in 13F-reported U.S. long-equity assets across 51 reported positions as of its 2026-03-31 13F-HR filing. Its largest disclosed positions are INSM (10.39%), ACAD (9.78%), PTCT (9.60%). Quarter over quarter (versus its 2025-12-31 filing) the fund opened 5 new positions, exited 3, added to 17, and trimmed 24.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
$653.9M
Long-equity book
51
Distinct positions
2026-03-31
Filed 2026-05-15
+5 / −3 / ↑17 / ↓24
vs 2025-12-31
| Name | Title / Status | Ownership | Type |
|---|
Top Adds (vs prior quarter)
- MIRUM PHARMACEUTICALS INC$17.7M +143.1%
- UNITED THERAPEUTICS CORP$8.9M +31.4%
- BICARA THERAPEUTICS INC$5.9M +117.9%
- ANNEXON INC$4.4M +36.5%
- SYNDAX PHARMACEUTICALS INC$3.5M +21.0%
Top Trims
- AMICUS THERAPEUTICS INC-$58.0M -78.3%
- INSMED INC-$17.3M -20.3%
- BIOGEN INC-$6.5M -20.1%
- DENALI THERAPEUTICS INC-$6.1M -57.5%
- PTC THERAPEUTICS INC-$5.9M -8.6%
New Positions
- CELLDEX THERAPEUTICS INC$9.4M
- CYTOKINETICS INC$2.1M
- VERASTEM INC$1.3M
- MADRIGAL PHARMACEUTICALS INC$935.4K
- XERIS BIOPHARMA HOLDINGS INC$605.6K
Exited Positions
- GOSSAMER BIO INC$13.9M
- GENERATION BIO CO$85.5K
- AKARI THERAPEUTICS PLC-ADR$42.2K
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | INSMED INC | INSM | 457669307 | $67.9M | 10.39% | 415,269 | SH |
| 2 | ACADIA PHARMACEUTICALS INC | ACAD | 004225108 | $63.9M | 9.78% | 2,872,695 | SH |
| 3 | PTC THERAPEUTICS INC | PTCT | 69366J200 | $62.8M | 9.60% | 921,607 | SH |
| 4 | BIOMARIN PHARMACEUTICAL INC | BMRN | 09061G101 | $38.7M | 5.92% | 685,182 | SH |
| 5 | UNITED THERAPEUTICS CORP | UTHR | 91307C102 | $37.2M | 5.70% | 62,809 | SH |
| 6 | ANAPTYSBIO INC | ANAB | 032724106 | $35.4M | 5.41% | 638,161 | SH |
| 7 | MIRUM PHARMACEUTICALS INC | MIRM | 604749101 | $30.0M | 4.59% | 325,175 | SH |
| 8 | DYNE THERAPEUTICS INC | DYN | 26818M108 | $30.0M | 4.58% | 1,652,972 | SH |
| 9 | BIOGEN INC | BIIB | 09062X103 | $25.8M | 3.95% | 140,719 | SH |
| 10 | DISC MEDICINE INC | IRON | 254604101 | $25.7M | 3.93% | 401,719 | SH |
| 11 | IOVANCE BIOTHERAPEUTICS INC | IOVA | 462260100 | $22.3M | 3.41% | 6,349,563 | SH |
| 12 | SYNDAX PHARMACEUTICALS INC | SNDX | 87164F105 | $20.2M | 3.09% | 864,986 | SH |
| 13 | ANNEXON INC | ANNX | 03589W102 | $16.3M | 2.50% | 2,948,090 | SH |
| 14 | AMICUS THERAPEUTICS INC | FOLD | 03152W109 | $16.1M | 2.46% | 1,113,045 | SH |
| 15 | NOVOCURE LTD | NVCR | G6674U108 | $14.0M | 2.13% | 1,280,439 | SH |
| 16 | ULTRAGENYX PHARMACEUTICAL IN | RARE | 90400D108 | $12.5M | 1.91% | 596,495 | SH |
| 17 | PROTHENA CORP PLC | PRTA | G72800108 | $11.7M | 1.80% | 1,208,568 | SH |
| 18 | BICARA THERAPEUTICS INC | BCAX | 055477103 | $10.9M | 1.67% | 550,408 | SH |
| 19 | CELLDEX THERAPEUTICS INC | CLDX | 15117B202 | $9.4M | 1.44% | 296,408 | SH |
| 20 | CAREDX INC | CDNA | 14167L103 | $9.2M | 1.41% | 531,870 | SH |
| 21 | ALKERMES PLC | ALKS | G01767105 | $8.6M | 1.31% | 242,560 | SH |
| 22 | COMPASS THERAPEUTICS INC | CMPX | 20454B104 | $8.0M | 1.23% | 1,514,504 | SH |
| 23 | AGIOS PHARMACEUTICALS INC | AGIO | 00847X104 | $7.2M | 1.11% | 213,601 | SH |
| 24 | ALIGN TECHNOLOGY INC | ALGN | 016255101 | $7.1M | 1.09% | 41,520 | SH |
| 25 | CAPRICOR THERAPEUTICS INC | CAPR | 14070B309 | $7.0M | 1.07% | 229,763 | SH |
| 26 | TRAVERE THERAPEUTICS INC | TVTX | 89422G107 | $6.8M | 1.05% | 230,453 | SH |
| 27 | TAYSHA GENE THERAPIES INC | TSHA | 877619106 | $6.2M | 0.95% | 1,391,382 | SH |
| 28 | ACLARIS THERAPEUTICS INC | ACRS | 00461U105 | $6.1M | 0.93% | 1,613,430 | SH |
| 29 | DENALI THERAPEUTICS INC | DNLI | 24823R105 | $4.5M | 0.69% | 234,582 | SH |
| 30 | XENON PHARMACEUTICALS INC | XENE | 98420N105 | $3.0M | 0.46% | 51,345 | SH |
| 31 | ORUKA THERAPEUTICS INC | ORKA | 687604108 | $2.9M | 0.45% | 59,985 | SH |
| 32 | STOKE THERAPEUTICS INC | STOK | 86150R107 | $2.8M | 0.42% | 84,631 | SH |
| 33 | EDWARDS LIFESCIENCES CORP | EW | 28176E108 | $2.7M | 0.41% | 33,640 | SH |
| 34 | NEUROCRINE BIOSCIENCES INC | NBIX | 64125C109 | $2.4M | 0.37% | 18,117 | SH |
| 35 | NUVATION BIO INC | NUVB | 67080N101 | $2.2M | 0.33% | 508,846 | SH |
| 36 | CYTOKINETICS INC | CYTK | 23282W605 | $2.1M | 0.32% | 32,195 | SH |
| 37 | EHEALTH INC | EHTH | 28238P109 | $1.9M | 0.29% | 1,482,797 | SH |
| 38 | CRISPR THERAPEUTICS AG | CRSP | H17182108 | $1.9M | 0.29% | 39,605 | SH |
| 39 | BIONTECH SE-ADR | BNTX | 09075V102 | $1.7M | 0.27% | 19,614 | SH |
| 40 | PYXIS ONCOLOGY INC | PYXS | 747324101 | $1.5M | 0.23% | 1,010,510 | SH |
| 41 | VERASTEM INC | VSTM | 92337C203 | $1.3M | 0.20% | 246,093 | SH |
| 42 | BICYCLE THERAPEUTICS PLC-ADR | BCYC | 088786108 | $936.8K | 0.14% | 201,890 | SH |
| 43 | MADRIGAL PHARMACEUTICALS INC | MDGL | 558868105 | $935.4K | 0.14% | 1,787 | SH |
| 44 | HUMANA INC | HUM | 444859102 | $691.0K | 0.11% | 3,985 | SH |
| 45 | COMPASS PATHWAYS PLC ADR | CMPS | 20451W101 | $639.4K | 0.10% | 115,616 | SH |
| 46 | XERIS BIOPHARMA HOLDINGS INC | XERS | 98422E103 | $605.6K | 0.09% | 104,410 | SH |
| 47 | ABEONA THERAPEUTICS INC | ABEO | 00289Y206 | $487.7K | 0.07% | 108,865 | SH |
| 48 | INSPIRE MEDICAL SYSTEMS INC | INSP | 457730109 | $452.5K | 0.07% | 8,772 | SH |
| 49 | UROGEN PHARMA LTD | URGN | M96088105 | $440.5K | 0.07% | 24,500 | SH |
| 50 | PROQR THERAPEUTICS NV | PRQR | N71542109 | $305.9K | 0.05% | 188,807 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-03-31 | 2026-05-15 | $653.9M | 51 | 0001306923-26-000004 |
| 2025-12-31 | 2026-02-17 | $718.4M | 49 | 0001306923-26-000002 |
| 2025-09-30 | 2025-11-14 | $540.4M | 44 | 0001306923-25-000019 |