Palo Alto Investors LP — 13F Holdings & Portfolio
CIK 1306923 · latest 13F-HR filed 2026-08-19
Palo Alto Investors LP manages $723.7M in 13F-reported U.S. long-equity assets across 52 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are PTCT (10.36%), ACAD (10.01%), INSM (6.10%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 3 new positions and exited 2; 32 existing positions rose in reported value and 9 fell.
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.
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AUM
$723.7M
Long-equity book
Holdings
52
Distinct positions
Period
2026-06-30
Filed 2026-08-19
Q/Q Activity
+3 / −2 / ↑32 / ↓9
vs 2026-03-31
Portfolio charts
Latest quarter's book, what changed, and how the portfolio has evolved across filings.
Portfolio map
Q2 26PTCT10.4% · -0%ACAD10.0% · -0%INSM6.1% · -0%MIRM5.6% · +7%ANAB5.6% · -5%BMRN5.4% · -0%DYN5.1% · -0%UTHR4.7% · -0%IRON4.2% · +4%BIIB4.2% · -0%IOVA3.0% · -17%RARE2.8% · 0%NVCR2.7% · 0%SNDX2.6% · 0%ANNX2.3% · 0%BCAX2.3% · 0%CDNA2.1% · 0%CLDX2.1% · +35%CMPX1.8% · +285%ALKS1.8% · 0%TRAX1.7% · newPRTA1.5% · -5%TVTX1.3% · -27%TSHA1.3% · 0%ACRS1.2% · 0%AGIO1.1% · 0%CAPR0.8% · 0%ALGN0.7% · -24%ORKA0.4% · -44%XENE0.4% · 0%NBIX0.4% · 0%EW0.4% · 0%STOK0.4% · 0%CYTK0.4% · 0%PYXS0.4% · -14%EHTH0.3% · 0%CRSP0.3% · 0%SGMT0.3% · newNUVB0.3% · -36%BNTX0.3% · 0%CMPS0.2% · 0%HUM0.2% · 0%NAMS0.2% · newVSTM0.2% · +26%MDGL0.1% · 0%URGN0.1% · 0%BCYC0.1% · 0%XERS0.1% · 0%ABEO0.1% · 0%INSP0.1% · 0%PRQR0.0% · 0%ALDX0.0% · 0%
Box size = position value; colour = change in share count vs the prior quarter (green added, red trimmed, blue new). Rows split across managers or share classes are combined. Click a box for the stock.
Sector mix
% of 13F valueSectors from each company's SIC code; funds and ETFs grouped separately.
Biggest buys and sells
Q1 26 → Q2 26Estimated from the change in shares held × the quarter-end price, so price moves alone don't count as buying. New and exited positions are included.
13F assets and positions
4 quartersTotal reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.
Top positions over time
reported valueThe eight largest current positions, valued at each quarter end.
Concentration
top 10 = 61.3%Cumulative share of the portfolio held in the largest N positions.
Firm Profile & Key People
As of the firm’s regulatory filing dated Mar 27, 2026.
Assets Under Management
$696.0M
Discretionary
$696.0M
Employees
10
Accounts
13
Address
101 UNIVERSITY AVE
SUITE 200
PALO ALTO, CA 94301-1638
SUITE 200
PALO ALTO, CA 94301-1638
Phone
(650) 325-0772
Website
| Name | Title / Status | Ownership | Type |
|---|---|---|---|
| LEE, PATRICK, YUARN-BOR Control | TRUSTEE OF PATRICK Y LEE DECLARATION OF TRUST since Mar 2018 | Less than 5% | Individual |
| NGUYEN-DINH, ANGELA, ELIZABETH Control | CHIEF COMPLIANCE OFFICER since Apr 2016 | Less than 5% | Individual |
| PALO ALTO INVESTORS GP LLC Control | GENERAL PARTNER since Mar 2018 | Less than 5% | Domestic Entity |
| PATRICK Y LEE DECLARATION OF TRUST Control | LIMITED PARTNER since Mar 2018 | 50–75% | Domestic Entity |
| YUN, ANTHONY, JOONKYOO Control | TRUSTEE OF YUN-BAZAR FAMILY TRUST since Mar 2018 | Less than 5% | Individual |
| YUN-BAZAR FAMILY TRUST Control | LIMITED PARTNER since Mar 2018 | 50–75% | Domestic Entity |
| LEE, PATRICK, YUARN-BOR Control Indirect owner via PALO ALTO INVESTORS GP LLC | MANAGER since Mar 2018 | General partner, trustee or manager | Individual |
| LEE, PATRICK, YUARN-BOR Control Indirect owner via PATRICK Y. LEE DECLARATION OF TRUST | TRUSTEE since Mar 2018 | General partner, trustee or manager | Individual |
| PATRICK Y. LEE DECLARATION OF TRUST Control Indirect owner via PALO ALTO INVESTORS GP LLC | MEMBER since Mar 2018 | 50–75% | Domestic Entity |
| YUN, ANTHONY, JOONKYOO Control Indirect owner via PALO ALTO INVESTORS GP LLC | MANAGER since Mar 2018 | General partner, trustee or manager | Individual |
| YUN, ANTHONY, JOONKYOO Control Indirect owner via YUN-BAZAR FAMILY TRUST | TRUSTEE since Mar 2018 | General partner, trustee or manager | Individual |
| YUN-BAZAR FAMILY TRUST Control Indirect owner via PALO ALTO INVESTORS GP LLC | MEMBER since Mar 2018 | 50–75% | Domestic Entity |
Ownership & leadership changes · 12 filings with changes since Mar 30, 2012
From the firm’s regulatory filings, newest first. Dates are filing dates: a filing that no longer lists someone does not say when they left.
Mar 27, 2026 filing
- ChangedLEE, PATRICK, YUARN-BOR · now a control person
- ChangedLEE, PATRICK, YUARN-BOR · indirect via PATRICK Y. LEE DECLARATION OF TRUST: now a control person
- ChangedYUN, ANTHONY, JOONKYOO · now a control person
- ChangedYUN, ANTHONY, JOONKYOO · indirect via YUN-BAZAR FAMILY TRUST: now a control person
Jun 2, 2023 filing
- AddedLEE, PATRICK, YUARN-BOR · TRUSTEE · General partner, trustee or manager · indirect via PATRICK Y. LEE DECLARATION OF TRUST
- AddedPATRICK Y LEE DECLARATION OF TRUST · LIMITED PARTNER · 50–75% · control person
- AddedYUN, ANTHONY, JOONKYOO · TRUSTEE · General partner, trustee or manager · indirect via YUN-BAZAR FAMILY TRUST
- AddedYUN-BAZAR FAMILY TRUST · LIMITED PARTNER · 50–75% · control person
- Listed againLEE, PATRICK, YUARN-BOR · TRUSTEE OF PATRICK Y LEE DECLARATION OF TRUST · Less than 5%
- Listed againYUN, ANTHONY, JOONKYOO · TRUSTEE OF YUN-BAZAR FAMILY TRUST · Less than 5%
- ChangedLEE, PATRICK, YUARN-BOR · indirect via PALO ALTO INVESTORS GP LLC: title CO-MANAGING MEMBER → MANAGER; ownership 50–75% → General partner, trustee or manager
- ChangedPALO ALTO INVESTORS GP LLC · title GENERAL PARNTER → GENERAL PARTNER; ownership 75% or more → Less than 5%
- ChangedPATRICK Y. LEE DECLARATION OF TRUST · indirect via PALO ALTO INVESTORS GP LLC: title CO-MANAGING MEMBER → MEMBER
- ChangedYUN, ANTHONY, JOONKYOO · indirect via PALO ALTO INVESTORS GP LLC: title CO-MANAGING MEMBER → MANAGER; ownership 50–75% → General partner, trustee or manager
- ChangedYUN-BAZAR FAMILY TRUST · indirect via PALO ALTO INVESTORS GP LLC: title CO-MANAGING MEMBER → MEMBER
Mar 31, 2023 filing
- No longer listedLEE, PATRICK, YUARN-BOR · CO-MANAGING MEMBER · 50–75% · indirect via PAI LLC · control person · listed since Mar 2018
- No longer listedPAI LLC · GENERAL PARNTER · 75% or more · control person · listed since Mar 2018
- No longer listedYUN, ANTHONY, JOONKYOO · CO-MANAGING MEMBER · 50–75% · indirect via PAI LLC · control person · listed since Mar 2018
- AddedLEE, PATRICK, YUARN-BOR · CO-MANAGING MEMBER · 50–75% · indirect via PALO ALTO INVESTORS GP LLC · control person
- AddedPALO ALTO INVESTORS GP LLC · GENERAL PARNTER · 75% or more · control person
- AddedPATRICK Y. LEE DECLARATION OF TRUST · CO-MANAGING MEMBER · 50–75% · indirect via PALO ALTO INVESTORS GP LLC · control person
- AddedYUN, ANTHONY, JOONKYOO · CO-MANAGING MEMBER · 50–75% · indirect via PALO ALTO INVESTORS GP LLC · control person
- AddedYUN-BAZAR FAMILY TRUST · CO-MANAGING MEMBER · 50–75% · indirect via PALO ALTO INVESTORS GP LLC · control person
May 11, 2022 filing
- No longer listedLEE, PATRICK, YUARN-BOR · CO-MANAGING MEMBER · 25–50% · control person · listed since Jan 2013
- No longer listedYUN, ANTHONY, JOONKYOO · CO-MANAGING MEMBER · 25–50% · control person · listed since Jan 2013
- AddedLEE, PATRICK, YUARN-BOR · CO-MANAGING MEMBER · 50–75% · indirect via PAI LLC · control person
- AddedPAI LLC · GENERAL PARNTER · 75% or more · control person
- AddedYUN, ANTHONY, JOONKYOO · CO-MANAGING MEMBER · 50–75% · indirect via PAI LLC · control person
Mar 31, 2022 filing
- ChangedNGUYEN-DINH, ANGELA, ELIZABETH · now a control person
Apr 19, 2016 filing
- No longer listedWU, KAI, C · CHIEF FINANCIAL OFFICER/CHIEF COMPLIANCE OFFICER · Less than 5% · listed since Feb 2014
- AddedNGUYEN-DINH, ANGELA, ELIZABETH · CHIEF COMPLIANCE OFFICER · Less than 5%
Mar 30, 2016 filing
- No longer listedEDWARDS, WILLIAM, LELAND · FOUNDER · 25–50% · control person · listed since Jan 2013
Feb 26, 2015 filing
- ChangedEDWARDS, WILLIAM, LELAND · now a control person
- ChangedWU, KAI, C · title CHIEF COMPLIANCE OFFICER → CHIEF FINANCIAL OFFICER/CHIEF COMPLIANCE OFFICER
Apr 11, 2014 filing
- No longer listedSMITH, SCOTT, RANDALL · CHIEF OPERATING OFFICER · Less than 5% · control person · listed since Feb 2007
- ChangedEDWARDS, WILLIAM, LELAND · title MEMBER → FOUNDER
Feb 5, 2014 filing
- AddedWU, KAI, C · CHIEF COMPLIANCE OFFICER · Less than 5%
- ChangedSMITH, SCOTT, RANDALL · title CHIEF OPERATING OFFICER, CHIEF COMPLIANCE OFFICER → CHIEF OPERATING OFFICER
Older changes (3 more filings)
Feb 4, 2013 filing
- No longer listedEDWARDS, WILLIAM, LELAND · SHAREHOLDER · 75% or more · indirect via PALO ALTO INVESTORS · control person · listed since Nov 1989
- No longer listedPALO ALTO INVESTORS · MANAGER AND MEMBER · Less than 5% · control person · listed since Nov 2000
- ChangedEDWARDS, WILLIAM, LELAND · title CHAIRMAN, CHIEF EXECUTIVE OFFICER AND CHIEF INVESTMENT OFFICER OF ADVISOR AND MANAGER, MEMBER → MEMBER; no longer a control person
- ChangedLEE, PATRICK, YUARN-BOR · title MEMBER → CO-MANAGING MEMBER; ownership 10–25% → 25–50%; now a control person
- ChangedSMITH, SCOTT, RANDALL · title CHIEF COMPLIANCE OFFICER → CHIEF OPERATING OFFICER, CHIEF COMPLIANCE OFFICER
- ChangedYUN, ANTHONY, JOONKYOO · title PRESIDENT OF PALO ALTO INVESTORS, LLC, PRESIDENT OF PALO ALTO INVESTORS, MANAGER, MEMBER → CO-MANAGING MEMBER; ownership 10–25% → 25–50%; now a control person
May 17, 2012 filing
- No longer listedSHAMIA, MARK, RAMSEY · CHIEF OPERATING OFFICER, MEMBER · Less than 5% · control person · listed since Sep 2006
Mar 30, 2012 filing (earliest on record)
- ListedEDWARDS, WILLIAM, LELAND · CHAIRMAN, CHIEF EXECUTIVE OFFICER AND CHIEF INVESTMENT OFFICER OF ADVISOR AND MANAGER, MEMBER · 25–50% · control person
- ListedEDWARDS, WILLIAM, LELAND · SHAREHOLDER · 75% or more · indirect via PALO ALTO INVESTORS · control person
- ListedLEE, PATRICK, YUARN-BOR · MEMBER · 10–25%
- ListedPALO ALTO INVESTORS · MANAGER AND MEMBER · Less than 5% · control person
- ListedSHAMIA, MARK, RAMSEY · CHIEF OPERATING OFFICER, MEMBER · Less than 5% · control person
- ListedSMITH, SCOTT, RANDALL · CHIEF COMPLIANCE OFFICER · Less than 5% · control person
- ListedYUN, ANTHONY, JOONKYOO · PRESIDENT OF PALO ALTO INVESTORS, LLC, PRESIDENT OF PALO ALTO INVESTORS, MANAGER, MEMBER · 10–25%
Quarter-over-quarter changes
Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.
Top Adds (vs prior quarter)
- PTC THERAPEUTICS INC$12.2M +19.4%
- MIRUM PHARMACEUTICALS INC$10.8M +35.9%
- ACADIA PHARMACEUTICALS INC$8.5M +13.3%
- ULTRAGENYX PHARMACEUTICAL IN$7.4M +59.4%
- DYNE THERAPEUTICS INC$6.6M +22.1%
Top Trims
- INSMED INC-$23.8M -35.0%
- UNITED THERAPEUTICS CORP-$3.3M -8.9%
- ALIGN TECHNOLOGY INC-$1.8M -25.6%
- CAPRICOR THERAPEUTICS INC-$1.5M -20.8%
- SYNDAX PHARMACEUTICALS INC-$1.3M -6.4%
New Positions
Show all 3 →Palo Alto Investors LP Holdings (2026-06-30)
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 | PTC THERAPEUTICS INC | PTCT | 69366J200 | $75.0M | 10.36% | 918,846 | SH |
| 2 | ACADIA PHARMACEUTICALS INC | ACAD | 004225108 | $72.5M | 10.01% | 2,864,096 | SH |
| 3 | INSMED INC | INSM | 457669307 | $44.1M | 6.10% | 413,980 | SH |
| 4 | MIRUM PHARMACEUTICALS INC | MIRM | 604749101 | $40.8M | 5.64% | 348,808 | SH |
| 5 | ANAPTYSBIO INC | ANAB | 032724106 | $40.7M | 5.63% | 603,489 | SH |
| 6 | BIOMARIN PHARMACEUTICAL INC | BMRN | 09061G101 | $39.1M | 5.40% | 682,777 | SH |
| 7 | DYNE THERAPEUTICS INC | DYN | 26818M108 | $36.6M | 5.06% | 1,647,521 | SH |
| 8 | UNITED THERAPEUTICS CORP | UTHR | 91307C102 | $33.9M | 4.69% | 62,587 | SH |
| 9 | DISC MEDICINE INC | IRON | 254604101 | $30.5M | 4.21% | 416,646 | SH |
| 10 | BIOGEN INC | BIIB | 09062X103 | $30.3M | 4.19% | 140,279 | SH |
| 11 | IOVANCE BIOTHERAPEUTICS INC | IOVA | 462260100 | $22.0M | 3.04% | 5,296,209 | SH |
| 12 | ULTRAGENYX PHARMACEUTICAL IN | RARE | 90400D108 | $19.9M | 2.75% | 596,495 | SH |
| 13 | NOVOCURE LTD | NVCR | G6674U108 | $19.4M | 2.68% | 1,280,439 | SH |
| 14 | SYNDAX PHARMACEUTICALS INC | SNDX | 87164F105 | $18.9M | 2.61% | 864,986 | SH |
| 15 | ANNEXON INC | ANNX | 03589W102 | $16.8M | 2.33% | 2,948,090 | SH |
| 16 | BICARA THERAPEUTICS INC | BCAX | 055477103 | $16.3M | 2.26% | 550,408 | SH |
| 17 | CAREDX INC | CDNA | 14167L103 | $15.2M | 2.09% | 531,870 | SH |
| 18 | CELLDEX THERAPEUTICS INC | CLDX | 15117B202 | $14.9M | 2.06% | 399,856 | SH |
| 19 | COMPASS THERAPEUTICS INC | CMPX | 20454B104 | $12.8M | 1.76% | 5,831,813 | SH |
| 20 | ALKERMES PLC | ALKS | G01767105 | $12.7M | 1.76% | 242,560 | SH |
| 21 | FIRST TRACKS BIOTHERAPEUTICS | TRAX | 337185102 | $12.1M | 1.68% | 603,489 | SH |
| 22 | PROTHENA CORP PLC | PRTA | G72800108 | $11.2M | 1.55% | 1,143,155 | SH |
| 23 | TRAVERE THERAPEUTICS INC | TVTX | 89422G107 | $9.5M | 1.32% | 167,525 | SH |
| 24 | TAYSHA GENE THERAPIES INC | TSHA | 877619106 | $9.5M | 1.31% | 1,391,382 | SH |
| 25 | ACLARIS THERAPEUTICS INC | ACRS | 00461U105 | $8.5M | 1.18% | 1,613,430 | SH |
| 26 | AGIOS PHARMACEUTICALS INC | AGIO | 00847X104 | $7.9M | 1.10% | 213,601 | SH |
| 27 | CAPRICOR THERAPEUTICS INC | CAPR | 14070B309 | $5.5M | 0.76% | 229,763 | SH |
| 28 | ALIGN TECHNOLOGY INC | ALGN | 016255101 | $5.3M | 0.73% | 31,389 | SH |
| 29 | ORUKA THERAPEUTICS INC - Restricted | ORKA | 687604108 | $3.2M | 0.44% | 33,546 | SH |
| 30 | XENON PHARMACEUTICALS INC | XENE | 98420N105 | $3.1M | 0.43% | 51,345 | SH |
| 31 | NEUROCRINE BIOSCIENCES INC | NBIX | 64125C109 | $3.1M | 0.42% | 18,117 | SH |
| 32 | EDWARDS LIFESCIENCES CORP | EW | 28176E108 | $3.0M | 0.42% | 33,640 | SH |
| 33 | STOKE THERAPEUTICS INC | STOK | 86150R107 | $2.8M | 0.38% | 84,631 | SH |
| 34 | CYTOKINETICS INC | CYTK | 23282W605 | $2.7M | 0.38% | 32,195 | SH |
| 35 | PYXIS ONCOLOGY INC | PYXS | 747324101 | $2.6M | 0.36% | 864,277 | SH |
| 36 | EHEALTH INC | EHTH | 28238P109 | $2.2M | 0.31% | 1,482,797 | SH |
| 37 | CRISPR THERAPEUTICS AG | CRSP | H17182108 | $2.2M | 0.30% | 39,605 | SH |
| 38 | SAGIMET BIOSCIENCES INC-A | SGMT | 786700104 | $1.9M | 0.27% | 250,000 | SH |
| 39 | NUVATION BIO INC | NUVB | 67080N101 | $1.9M | 0.26% | 326,609 | SH |
| 40 | BIONTECH SE-ADR | BNTX | 09075V102 | $1.8M | 0.25% | 19,614 | SH |
| 41 | COMPASS PATHWAYS PLC ADR | CMPS | 20451W101 | $1.6M | 0.23% | 115,616 | SH |
| 42 | HUMANA INC | HUM | 444859102 | $1.6M | 0.22% | 3,985 | SH |
| 43 | NEWAMSTERDAM PHARMA CO NV | NAMS | N62509109 | $1.5M | 0.21% | 44,359 | SH |
| 44 | VERASTEM INC | VSTM | 92337C203 | $1.2M | 0.16% | 309,685 | SH |
| 45 | MADRIGAL PHARMACEUTICALS INC | MDGL | 558868105 | $959.5K | 0.13% | 1,787 | SH |
| 46 | UROGEN PHARMA LTD | URGN | M96088105 | $901.6K | 0.12% | 24,500 | SH |
| 47 | BICYCLE THERAPEUTICS PLC-ADR | BCYC | 088786108 | $856.0K | 0.12% | 201,890 | SH |
| 48 | XERIS BIOPHARMA HOLDINGS INC | XERS | 98422E103 | $826.9K | 0.11% | 104,410 | SH |
| 49 | ABEONA THERAPEUTICS INC | ABEO | 00289Y206 | $672.8K | 0.09% | 108,865 | SH |
| 50 | INSPIRE MEDICAL SYSTEMS INC | INSP | 457730109 | $391.3K | 0.05% | 8,772 | SH |
Filing History
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-18 | $723.7M | 52 | 0002073679-26-000101 |
| 2026-06-30 | 2026-08-17 | $723.7M | 52 | 0002073679-26-000096 |
| 2026-06-30 | 2026-08-19 | $723.7M | 52 | 0002073679-26-000102 |
| 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 |
Filer Information
Address
101 UNIVERSITY AVESUITE 200
PALO ALTO, CA 94301
Phone
(650) 325-0772
Filing Manager
Palo Alto Investors LP
PALO ALTO, CA
Signatory
Angela Nguyen Dinh
Chief Compliance Officer