CIK: 0001306923
Total reported value
$653.9M
Reporting period: 2026-03-31 · Number of holdings: 51
Palo Alto Investors LP disclosed 51 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $653.9M and a quarterly turnover rate of 30.8%.
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Palo Alto Investors LP's disclosed holdings carry a Herfindahl concentration index of 0.053 — mathematically equivalent to about 19 equally-sized positions, well below its 51 actual disclosed holdings. That gap points to a strategy built around a small core of high-conviction bets rather than broad diversification.
Position sizes vary widely across the portfolio (a coefficient of variation of 1.32), with a handful of outsized bets alongside many smaller positions.
Recent activity leans toward adding more aggressively to already-large existing positions than to newly initiated ones (a 2.1 percentage-point tilt) — a pattern consistent with a momentum-following approach.
Sector classification currently covers about 52% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.
Trim AM6
-78.6% -$58.0M
Add MIRM
+107.9% $17.7M
Add UTHR
+7.9% $8.9M
Trim INSM
-15.2% -$17.3M
Add BCAX
+84.3% $5.9M
Add ANNX
+23.7% $4.4M
| # | Ticker | Issuer | Asset Subclass | Weight | Weight Change | Shares Change | 4Q Trend |
|---|---|---|---|---|---|---|---|
| 1 | INSM | Insmed INC | Stock-Healthcare | 10.39% | -1.47% | -15.16% | |
| 2 | ACAD | Acadia Pharmaceuticals INC | Stock-Healthcare | 9.78% | +0.54% | +15.65% | |
| 3 | PTCT | Ptc Therapeutics INC | Stock-Healthcare | 9.60% | +0.04% | +1.96% | |
| 4 | BMRN | Biomarin Pharmaceutical INC | Stock-Healthcare | 5.92% | -0.25% | -8.18% | |
| 5 | UTHR | United Therapeutics CORP | Stock-Healthcare | 5.70% | +1.75% | +7.95% | |
| 6 | ANAB | Anaptysbio INC | Stock-Other | 5.41% | +0.75% | -7.52% | |
| 7 | MIRM | Mirum Pharmaceuticals INC | Stock-Other | 4.59% | +2.87% | +107.88% | |
| 8 | DYN | Dyne Therapeutics INC | Stock-Other | 4.58% | +0.57% | +12.28% | |
| 9 | BIIB | Biogen INC | Stock-Healthcare | 3.95% | -0.55% | -23.34% | |
| 10 | IRON | Disc Medicine INC | Stock-Other | 3.93% | +0.42% | +26.54% | |
| 11 | IOVA | Iovance Biotherapeutics INC | Stock-Other | 3.41% | +0.71% | -10.78% | |
| 12 | SNDX | Syndax Pharmaceuticals INC | Stock-Other | 3.09% | +0.77% | +8.87% | |
| 13 | ANNX | Annexon INC | Stock-Other | 2.50% | +0.83% | +23.65% | |
| 14 | AM6 | Amicus Therapeutics INC | Stock-Other | 2.46% | -7.86% | -78.62% | |
| 15 | NVCR | NovoCure Limited | Stock-Healthcare | 2.13% | -0.21% | -1.43% | |
| 16 | RARE | Ultragenyx Pharmaceutical In | Stock-Other | 1.91% | +0.43% | +29.31% | |
| 17 | PRTA | Prothena Corporation plc | Stock-Other | 1.80% | +0.04% | -8.48% | |
| 18 | BCAX | Bicara Therapeutics INC | Stock-Other | 1.67% | +0.97% | +84.34% | |
| 19 | CLDX | Celldex Therapeutics INC | Stock-Other | 1.44% | +1.44% | NEW | |
| 20 | CDNA | Caredx INC | Stock-Other | 1.41% | +0.16% | +11.22% | |
| 21 | ALKS | Alkermes plc | Stock-Healthcare | 1.31% | +0.37% | — | |
| 22 | CMPX | Compass Therapeutics INC | Stock-Other | 1.23% | -0.66% | -40.20% | |
| 23 | AGIO | Agios Pharmaceuticals INC | Stock-Other | 1.11% | +0.30% | +0.52% | |
| 24 | ALGN | Align Technology INC | Stock-Healthcare | 1.09% | +0.19% | — | |
| 25 | CAPR | Capricor Therapeutics INC | Stock-Other | 1.07% | +0.16% | +1.53% | |
| 26 | TVTX | Travere Therapeutics INC | Stock-Other | 1.05% | +0.46% | +108.14% | |
| 27 | TSHA | Taysha Gene Therapies INC | Stock-Other | 0.95% | +0.04% | +17.60% | |
| 28 | ACRS | Aclaris Therapeutics INC | Stock-Other | 0.93% | +0.27% | +2.97% | |
| 29 | DNLI | Denali Therapeutics INC | Stock-Other | 0.69% | -0.78% | -63.42% | |
| 30 | XENE | Xenon Pharmaceuticals INC | Stock-Other | 0.46% | -0.14% | -46.80% | |
| 31 | ORKA | Oruka Therapeutics INC | Stock-Other | 0.45% | +0.20% | — | |
| 32 | STOK | Stoke Therapeutics INC | Stock-Other | 0.42% | +0.10% | +17.51% | |
| 33 | EW | Edwards Lifesciences CORP | Stock-Healthcare | 0.41% | +0.01% | — | |
| 34 | NBIX | Neurocrine Biosciences INC | Stock-Healthcare | 0.37% | — | — | |
| 35 | NUVB | Nuvation Bio INC | Stock-Other | 0.33% | -0.34% | -5.43% | |
| 36 | CYTK | Cytokinetics INC | Stock-Healthcare | 0.32% | +0.32% | NEW | |
| 37 | EHTH | Ehealth INC | Stock-Other | 0.29% | -0.69% | -3.18% | |
| 38 | CRSP | CRISPR Therapeutics AG | Stock-Healthcare | 0.29% | -0.01% | -3.93% | |
| 39 | BNTX | Biontech Se-adr | Stock-Other | 0.27% | +0.01% | — | |
| 40 | PYXS | Pyxis Oncology INC | Stock-Other | 0.23% | +0.06% | -2.59% | |
| 41 | VSTM | Verastem INC | Stock-Other | 0.20% | +0.20% | NEW | |
| 42 | BCYC | Bicycle Therapeutics Plc-adr | Stock-Other | 0.14% | -0.08% | -8.68% | |
| 43 | MDGL | Madrigal Pharmaceuticals INC | Stock-Healthcare | 0.14% | +0.14% | NEW | |
| 44 | HUM | Humana INC | Stock-Healthcare | 0.11% | -0.03% | — | |
| 45 | CMPS | Compass Pathways PLC | Stock-Other | 0.10% | -0.01% | — | |
| 46 | XERS | Xeris Biopharma Holdings INC | Stock-Other | 0.09% | +0.09% | NEW | |
| 47 | ABEO | Abeona Therapeutics INC | Stock-Other | 0.07% | — | — | |
| 48 | INSP | Inspire Medical Systems INC | Stock-Healthcare | 0.07% | -0.04% | — | |
| 49 | URGN | UroGen Pharma Ltd. | Stock-Other | 0.07% | -0.01% | — | |
| 50 | ✓ | Proqr Thrapeutics N V | Stock-Other | 0.05% | — | — |
Performance for Q3 2026
+9.6%
Performance Last 4 Quarters
+39.2%
Based on 76% of reported portfolio value with available pricing
| Period | Holdings | Total value | Stability | Top holdings |
|---|---|---|---|---|
| 2026-03-31 | 51 | $653.9M | 31 | |
| 2025-12-31 | 49 | $718.4M | 37 | |
| 2025-09-30 | 44 | $540.4M | 50 | |
| 2025-06-30 | 45 | $470.0M | 0 | |
| 2025-03-31 | 44 | $525.1M | 100 | |
| 2024-12-31 | 43 | $645.4M | 0 | |
| 2024-09-30 | 45 | $769.9M | 0 | |
| 2024-06-30 | 39 | $863.0M | 0 | |
| 2024-03-31 | 38 | $886.7M | 0 | |
| 2023-12-31 | 34 | $1.1B | 0 | |
| 2023-09-30 | 29 | $1.1B | 0 | |
| 2023-06-30 | 30 | $1.2B | 0 | |
| 2023-03-31 | 30 | $1.2B | 0 | |
| 2022-12-31 | 29 | $1.2B | 0 | |
| 2022-09-30 | 32 | $1.3B | 0 | |
| 2022-06-30 | 33 | $1.1B | 0 | |
| 2022-03-31 | 35 | $1.3B | 0 | |
| 2021-12-31 | 37 | $1.6B | 0 | |
| 2021-09-30 | 42 | $1.7B | 0 | |
| 2021-06-30 | 42 | $1.8B | 13 | |
| 2021-03-31 | 42 | $1.8B | 26 | |
| 2020-12-31 | 41 | $1.9B | 54 | |
| 2020-09-30 | 43 | $1.8B | 33 | |
| 2020-06-30 | 41 | $1.7B | 36 | |
| 2020-03-31 | 37 | $1.2B | 44 | |
| 2019-12-31 | 37 | $1.8B | 33 | |
| 2019-09-30 | 37 | $1.5B | 36 | |
| 2019-06-30 | 39 | $2.1B | 17 | |
| 2019-03-31 | 37 | $2.4B | 32 | |
| 2018-12-31 | 36 | $1.9B | 31 | |
| 2018-09-30 | 36 | $2.5B | 16 | |
| 2018-06-30 | 36 | $2.5B | 16 | |
| 2018-03-31 | 36 | $2.3B | 17 | |
| 2017-12-31 | 37 | $2.3B | 21 | |
| 2017-09-30 | 40 | $2.4B | 21 | |
| 2017-06-30 | 38 | $2.1B | 18 | |
| 2017-03-31 | 39 | $2.1B | 29 | |
| 2016-12-31 | 38 | $1.8B | 22 | |
| 2016-09-30 | 42 | $1.7B | 32 | |
| 2016-06-30 | 45 | $1.3B | 32 | |
| 2016-03-31 | 44 | $1.3B | 35 | |
| 2015-12-31 | 43 | $1.8B | 34 | |
| 2015-09-30 | 47 | $2.1B | 32 | |
| 2015-06-30 | 45 | $2.2B | 20 | |
| 2015-03-31 | 46 | $2.0B | 66 | |
| 2014-12-31 | 46 | $1.7B | 26 | |
| 2014-09-30 | 43 | $1.3B | 54 | |
| 2014-06-30 | 42 | $1.3B | 30 | |
| 2014-03-31 | 39 | $1.2B | 28 | 145884X205334D323251P |
| 2013-12-31 | 34 | $1.1B | 46 | |
| 2013-09-30 | 34 | $954.1M | 34 | |
| 2013-06-30 | 32 | $847.3M | 0 | 16833992928241323251P |
Palo Alto Investors LP's most significant position changes for 2026-03-31: Sold out: Gossamer Bio INC (GOSS); New buy: Celldex Therapeutics INC (CLDX); New buy: Cytokinetics INC (CYTK); New buy: Verastem INC (VSTM); New buy: Madrigal Pharmaceuticals INC (MDGL).
| # | Ticker | Issuer | Weight Change | Shares Change | Action |
|---|---|---|---|---|---|
| 1 | MIRM | Mirum Pharmaceuticals INC | +2.9% | +107.88% | Add |
| 2 | UTHR | United Therapeutics CORP | +1.8% | +7.95% | Add |
| 3 | BCAX | Bicara Therapeutics INC | +1% | +84.34% | Add |
| 4 | ANNX | Annexon INC | +0.8% | +23.65% | Add |
| 5 | SNDX | Syndax Pharmaceuticals INC | +0.8% | +8.87% | Add |
| 6 | ANAB | Anaptysbio INC | +0.8% | -7.52% | Trim |
| 7 | IOVA | Iovance Biotherapeutics INC | +0.7% | -10.78% | Trim |
| 8 | DYN | Dyne Therapeutics INC | +0.6% | +12.28% | Add |
| 9 | ACAD | Acadia Pharmaceuticals INC | +0.5% | +15.65% | Add |
| 10 | TVTX | Travere Therapeutics INC | +0.5% | +108.14% | Add |
| 11 | RARE | Ultragenyx Pharmaceutical In | +0.4% | +29.31% | Add |
| 12 | IRON | Disc Medicine INC | +0.4% | +26.54% | Add |
| 13 | ALKS | Alkermes plc | +0.4% | — | Unchanged |
| 14 | AGIO | Agios Pharmaceuticals INC | +0.3% | +0.52% | Add |
| 15 | ACRS | Aclaris Therapeutics INC | +0.3% | +2.97% | Add |
| 16 | ORKA | Oruka Therapeutics INC | +0.2% | — | Unchanged |
| 17 | ALGN | Align Technology INC | +0.2% | — | Unchanged |
| 18 | CAPR | Capricor Therapeutics INC | +0.2% | +1.53% | Add |
| 19 | CDNA | Caredx INC | +0.2% | +11.22% | Add |
| 20 | STOK | Stoke Therapeutics INC | +0.1% | +17.51% | Add |
| 21 | PYXS | Pyxis Oncology INC | +0.1% | -2.59% | Trim |
| 22 | PTCT | Ptc Therapeutics INC | 0% | +1.96% | Add |
| 23 | PRTA | Prothena Corporation plc | 0% | -8.48% | Trim |
| 24 | TSHA | Taysha Gene Therapies INC | 0% | +17.60% | Add |
| 25 | EW | Edwards Lifesciences CORP | 0% | — | Unchanged |
| 26 | BNTX | Biontech Se-adr | 0% | — | Unchanged |
| 27 | NBIX | Neurocrine Biosciences INC | — | — | Unchanged |
| 28 | CRSP | CRISPR Therapeutics AG | 0% | -3.93% | Trim |
| 29 | CMPS | Compass Pathways PLC | 0% | — | Unchanged |
| 30 | URGN | UroGen Pharma Ltd. | 0% | — | Unchanged |
| 31 | HUM | Humana INC | 0% | — | Unchanged |
| 32 | INSP | Inspire Medical Systems INC | 0% | — | Unchanged |
| 33 | BCYC | Bicycle Therapeutics Plc-adr | -0.1% | -8.68% | Trim |
| 34 | ALDX | Aldeyra Therapeutics INC | -0.1% | -30.94% | Trim |
| 35 | XENE | Xenon Pharmaceuticals INC | -0.1% | -46.80% | Trim |
| 36 | NVCR | NovoCure Limited | -0.2% | -1.43% | Trim |
| 37 | BMRN | Biomarin Pharmaceutical INC | -0.3% | -8.18% | Trim |
| 38 | NUVB | Nuvation Bio INC | -0.3% | -5.43% | Trim |
| 39 | BIIB | Biogen INC | -0.6% | -23.34% | Trim |
| 40 | CMPX | Compass Therapeutics INC | -0.7% | -40.20% | Trim |
| 41 | EHTH | Ehealth INC | -0.7% | -3.18% | Trim |
| 42 | DNLI | Denali Therapeutics INC | -0.8% | -63.42% | Trim |
| 43 | INSM | Insmed INC | -1.5% | -15.16% | Trim |
| 44 | AM6 | Amicus Therapeutics INC | -7.9% | -78.62% | Trim |
| 45 | GOSS | Gossamer Bio INC | — | EXIT | Sold out |
| 46 | CLDX | Celldex Therapeutics INC | — | NEW | New buy |
| 47 | CYTK | Cytokinetics INC | — | NEW | New buy |
| 48 | VSTM | Verastem INC | — | NEW | New buy |
| 49 | MDGL | Madrigal Pharmaceuticals INC | — | NEW | New buy |
| 50 | XERS | Xeris Biopharma Holdings INC | — | NEW | New buy |
| Period | Filed | Type | EDGAR |
|---|---|---|---|
| 2026-03-31 | 2026-05-15 | 13F-HR | View on EDGAR |
| 2025-12-31 | 2026-02-17 | 13F-HR | View on EDGAR |
| 2025-09-30 | 2025-11-14 | 13F-HR | View on EDGAR |
| 2025-06-30 | 2025-08-14 | 13F-HR | View on EDGAR |
| 2025-03-31 | 2025-05-15 | 13F-HR | View on EDGAR |
| 2024-12-31 | 2025-02-14 | 13F-HR | View on EDGAR |
| 2024-09-30 | 2024-11-14 | 13F-HR | View on EDGAR |
| 2024-06-30 | 2024-08-14 | 13F-HR | View on EDGAR |
| 2024-03-31 | 2024-05-15 | 13F-HR | View on EDGAR |
| 2023-12-31 | 2024-02-15 | Amendment | View on EDGAR |
| 2023-12-31 | 2024-02-14 | 13F-HR | View on EDGAR |
| 2023-09-30 | 2023-11-14 | 13F-HR | View on EDGAR |
| 2023-06-30 | 2023-08-14 | 13F-HR | View on EDGAR |
| 2023-03-31 | 2023-05-15 | 13F-HR | View on EDGAR |
| 2022-12-31 | 2023-02-14 | 13F-HR | View on EDGAR |
| 2022-09-30 | 2022-11-14 | 13F-HR | View on EDGAR |
| 2022-06-30 | 2022-08-15 | 13F-HR | View on EDGAR |
| 2022-03-31 | 2022-05-16 | 13F-HR | View on EDGAR |
| 2021-12-31 | 2022-02-14 | 13F-HR | View on EDGAR |
| 2021-09-30 | 2021-11-15 | 13F-HR | View on EDGAR |
| 2021-06-30 | 2021-08-16 | 13F-HR | View on EDGAR |
| 2021-03-31 | 2021-05-17 | 13F-HR | View on EDGAR |
| 2020-12-31 | 2021-02-16 | 13F-HR | View on EDGAR |
| 2020-09-30 | 2020-11-16 | 13F-HR | View on EDGAR |
| 2020-06-30 | 2020-08-14 | 13F-HR | View on EDGAR |
| 2020-03-31 | 2020-05-15 | 13F-HR | View on EDGAR |
| 2019-12-31 | 2020-04-08 | Amendment | View on EDGAR |
| 2019-12-31 | 2020-02-14 | 13F-HR | View on EDGAR |
| 2019-09-30 | 2019-11-14 | 13F-HR | View on EDGAR |
| 2019-06-30 | 2019-08-14 | 13F-HR | View on EDGAR |
| 2019-03-31 | 2019-07-30 | Amendment | View on EDGAR |
| 2019-03-31 | 2019-05-15 | 13F-HR | View on EDGAR |
| 2018-12-31 | 2019-02-14 | 13F-HR | View on EDGAR |
| 2018-09-30 | 2018-11-14 | 13F-HR | View on EDGAR |
| 2018-06-30 | 2018-08-14 | 13F-HR | View on EDGAR |
| 2018-03-31 | 2018-05-15 | 13F-HR | View on EDGAR |
| 2017-12-31 | 2018-02-14 | 13F-HR | View on EDGAR |
| 2017-09-30 | 2017-11-14 | 13F-HR | View on EDGAR |
| 2017-06-30 | 2017-08-14 | 13F-HR | View on EDGAR |
| 2017-03-31 | 2017-05-15 | 13F-HR | View on EDGAR |
| 2016-12-31 | 2017-02-15 | 13F-HR | View on EDGAR |
| 2016-09-30 | 2016-11-14 | 13F-HR | View on EDGAR |
| 2016-06-30 | 2016-08-16 | Amendment | View on EDGAR |
| 2016-06-30 | 2016-08-15 | 13F-HR | View on EDGAR |
| 2016-03-31 | 2016-05-16 | 13F-HR | View on EDGAR |
| 2015-12-31 | 2016-02-16 | 13F-HR | View on EDGAR |
| 2015-09-30 | 2015-11-16 | 13F-HR | View on EDGAR |
| 2015-06-30 | 2015-08-14 | 13F-HR | View on EDGAR |
| 2015-03-31 | 2015-05-15 | 13F-HR | View on EDGAR |
| 2014-12-31 | 2015-02-17 | 13F-HR | View on EDGAR |
| 2014-09-30 | 2014-11-13 | 13F-HR | View on EDGAR |
| 2014-06-30 | 2014-08-14 | 13F-HR | View on EDGAR |
| 2014-03-31 | 2014-05-16 | Amendment | View on EDGAR |
| 2014-03-31 | 2014-05-15 | 13F-HR | View on EDGAR |
| 2013-12-31 | 2014-02-13 | 13F-HR | View on EDGAR |
| 2013-09-30 | 2013-11-20 | Amendment | View on EDGAR |
| 2013-09-30 | 2013-11-13 | 13F-HR | View on EDGAR |
| 2013-06-30 | 2013-08-14 | 13F-HR | View on EDGAR |
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