Skip to content
Disclosery

Palo Alto Investors LP

Follow

13F filer, CIK 1306923, PALO ALTO, CA

Palo Alto Investors LP reported $653,863,097 across 51 holdings for the quarter ended 2026-03-31, in a 13F-HR filed 2026-05-15. Its ten largest share positions make up 63.85% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0001306923-26-000004

Period
2026-03-31
Reported value
$654M
Holdings
51
Top 10 weight
63.85%
New
5
Sold out
3

Largest buys vs the previous quarter

SecurityShares changeApprox. value
MIRMadded+168,754$15.6M
CLDXnew+296,408$9.4M
ACADadded+388,664$8.65M
IRONadded+84,263$5.39M
BCAXadded+251,833$5.01M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Largest sells vs the previous quarter

SecurityShares changeApprox. value
FOLDreduced-4,092,722-$59.2M
GOSSexited-4,471,592-$13.9M
INSMreduced-74,213-$12.1M
BIIBreduced-42,852-$7.86M
DNLIreduced-406,657-$7.81M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Holdings, Q1 2026

Share positions as resolved from 13F-HR 0001306923-26-000004, largest first. % of portfolio is the value over $653,863,097, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
INSMINSMED INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 1,940,993 shares; 2024Q4: 1,603,465 shares; 2025Q1: 987,153 shares; 2025Q2: 865,113 shares; 2025Q3: 491,805 shares; 2025Q4: 489,482 shares; 2026Q1: 415,269 shares 415,269$67.9M10.39%-74,213Timeline
ACADACADIA PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 2,523,956 shares; 2024Q4: 2,748,599 shares; 2025Q1: 2,663,925 shares; 2025Q2: 2,563,209 shares; 2025Q3: 2,466,684 shares; 2025Q4: 2,484,031 shares; 2026Q1: 2,872,695 shares 2,872,695$63.9M9.78%+388,664Timeline
PTCTPTC THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 264,469 shares; 2024Q4: 386,413 shares; 2025Q1: 404,196 shares; 2025Q2: 406,469 shares; 2025Q3: 862,613 shares; 2025Q4: 903,916 shares; 2026Q1: 921,607 shares 921,607$62.8M9.6%+17,691Timeline
BMRNBIOMARIN PHARMACEUTICAL INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 1,090,056 shares; 2024Q4: 1,067,266 shares; 2025Q1: 991,207 shares; 2025Q2: 840,470 shares; 2025Q3: 754,007 shares; 2025Q4: 746,256 shares; 2026Q1: 685,182 shares 685,182$38.7M5.92%-61,074Timeline
UTHRUNITED THERAPEUTICS CORP DELQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 183,246 shares; 2024Q4: 155,714 shares; 2025Q1: 105,228 shares; 2025Q2: 95,482 shares; 2025Q3: 58,186 shares; 2025Q4: 58,186 shares; 2026Q1: 62,809 shares 62,809$37.2M5.7%+4,623Timeline
ANABANAPTYSBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 843,971 shares; 2024Q4: 843,971 shares; 2025Q1: 1,020,713 shares; 2025Q2: 812,821 shares; 2025Q3: 673,520 shares; 2025Q4: 690,032 shares; 2026Q1: 638,161 shares 638,161$35.4M5.41%-51,871Timeline
MIRMMIRUM PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 64,700 shares; 2024Q4: 64,700 shares; 2025Q1: 64,700 shares; 2025Q2: 64,700 shares; 2025Q3: 64,700 shares; 2025Q4: 156,421 shares; 2026Q1: 325,175 shares 325,175$30M4.59%+168,754Timeline
DYNDYNE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 333,391 shares; 2025Q2: 264,976 shares; 2025Q3: 1,262,674 shares; 2025Q4: 1,472,197 shares; 2026Q1: 1,652,972 shares 1,652,972$30M4.58%+180,775Timeline
BIIBBIOGEN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 228,916 shares; 2024Q4: 190,148 shares; 2025Q1: 204,923 shares; 2025Q2: 205,759 shares; 2025Q3: 185,661 shares; 2025Q4: 183,571 shares; 2026Q1: 140,719 shares 140,719$25.8M3.95%-42,852Timeline
IRONDISC MEDICINE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 145,691 shares; 2025Q3: 224,300 shares; 2025Q4: 317,456 shares; 2026Q1: 401,719 shares 401,719$25.7M3.93%+84,263Timeline
IOVAIOVANCE BIOTHERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 3,041,685 shares; 2024Q4: 3,041,685 shares; 2025Q1: 3,211,314 shares; 2025Q2: 3,429,329 shares; 2025Q3: 7,618,132 shares; 2025Q4: 7,116,676 shares; 2026Q1: 6,349,563 shares 6,349,563$22.3M3.41%-767,113Timeline
SNDXSYNDAX PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 405,193 shares; 2024Q4: 405,193 shares; 2025Q1: 444,367 shares; 2025Q2: 444,367 shares; 2025Q3: 654,930 shares; 2025Q4: 794,507 shares; 2026Q1: 864,986 shares 864,986$20.2M3.09%+70,479Timeline
ANNXANNEXON INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 2,384,192 shares; 2026Q1: 2,948,090 shares 2,948,090$16.3M2.5%+563,898Timeline
FOLDAMICUS THERAPEUTICQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 8,145,311 shares; 2024Q4: 7,662,479 shares; 2025Q1: 7,345,002 shares; 2025Q2: 5,610,513 shares; 2025Q3: 5,367,798 shares; 2025Q4: 5,205,767 shares; 2026Q1: 1,113,045 shares 1,113,045$16.1M2.46%-4,092,722Timeline
NVCRNOVOCURE LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 593,540 shares; 2024Q4: 814,191 shares; 2025Q1: 1,002,061 shares; 2025Q2: 962,396 shares; 2025Q3: 1,256,159 shares; 2025Q4: 1,298,964 shares; 2026Q1: 1,280,439 shares 1,280,439$14M2.13%-18,525Timeline
RAREULTRAGENYX PHARMACEUTICAL INQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 48,750 shares; 2025Q3: 369,531 shares; 2025Q4: 461,294 shares; 2026Q1: 596,495 shares 596,495$12.5M1.91%+135,201Timeline
PRTAPROTHENA CORP PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 1,737,964 shares; 2024Q4: 1,737,964 shares; 2025Q1: 1,659,734 shares; 2025Q2: 1,274,753 shares; 2025Q3: 1,324,028 shares; 2025Q4: 1,320,510 shares; 2026Q1: 1,208,568 shares 1,208,568$11.7M1.8%-111,942Timeline
BCAXBICARA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 298,575 shares; 2026Q1: 550,408 shares 550,408$10.9M1.67%+251,833Timeline
CLDXCELLDEX THERAPEUTICS INC NEWQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 296,408 shares 296,408$9.4M1.44%newTimeline
CDNACAREDX INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 316,204 shares; 2025Q4: 478,220 shares; 2026Q1: 531,870 shares 531,870$9.23M1.41%+53,650Timeline
ALKSALKERMES PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 384,656 shares; 2024Q4: 289,308 shares; 2025Q1: 221,513 shares; 2025Q2: 221,021 shares; 2025Q3: 183,938 shares; 2025Q4: 242,560 shares; 2026Q1: 242,560 shares 242,560$8.58M1.31%0Timeline
CMPXCOMPASS THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 2,532,419 shares; 2026Q1: 1,514,504 shares 1,514,504$8.01M1.23%-1,017,915Timeline
AGIOAGIOS PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 276,578 shares; 2025Q2: 268,783 shares; 2025Q3: 265,497 shares; 2025Q4: 212,499 shares; 2026Q1: 213,601 shares 213,601$7.23M1.11%+1,102Timeline
ALGNALIGN TECHNOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 37,772 shares; 2024Q4: 37,772 shares; 2025Q1: 37,772 shares; 2025Q2: 37,772 shares; 2025Q3: 45,735 shares; 2025Q4: 41,520 shares; 2026Q1: 41,520 shares 41,520$7.12M1.09%0Timeline
CAPRCAPRICOR THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 226,304 shares; 2026Q1: 229,763 shares 229,763$6.98M1.07%+3,459Timeline
TVTXTRAVERE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 110,719 shares; 2024Q4: 110,719 shares; 2025Q1: 110,719 shares; 2025Q2: 110,719 shares; 2025Q3: 110,719 shares; 2025Q4: 110,719 shares; 2026Q1: 230,453 shares 230,453$6.85M1.05%+119,734Timeline
TSHATAYSHA GENE THERAPIES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 811,268 shares; 2024Q4: 811,268 shares; 2025Q1: 1,419,468 shares; 2025Q2: 1,246,033 shares; 2025Q3: 1,246,033 shares; 2025Q4: 1,183,195 shares; 2026Q1: 1,391,382 shares 1,391,382$6.22M0.95%+208,187Timeline
ACRSACLARIS THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 569,832 shares; 2024Q4: 569,832 shares; 2025Q1: 776,028 shares; 2025Q2: 1,390,028 shares; 2025Q3: 1,566,840 shares; 2025Q4: 1,566,840 shares; 2026Q1: 1,613,430 shares 1,613,430$6.05M0.93%+46,590Timeline
DNLIDENALI THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 239,809 shares; 2025Q3: 408,006 shares; 2025Q4: 641,239 shares; 2026Q1: 234,582 shares 234,582$4.5M0.69%-406,657Timeline
XENEXENON PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 96,519 shares; 2026Q1: 51,345 shares 51,345$2.99M0.46%-45,174Timeline
ORKAORUKA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 59,985 shares; 2025Q4: 59,985 shares; 2026Q1: 59,985 shares 59,985$2.94M0.45%0Timeline
STOKSTOKE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 125,861 shares; 2024Q4: 125,861 shares; 2025Q1: 125,861 shares; 2025Q2: 125,861 shares; 2025Q3: 105,427 shares; 2025Q4: 72,022 shares; 2026Q1: 84,631 shares 84,631$2.76M0.42%+12,609Timeline
EWEDWARDS LIFESCIENCES CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 39,473 shares; 2024Q4: 39,473 shares; 2025Q1: 39,473 shares; 2025Q2: 39,473 shares; 2025Q3: 33,640 shares; 2025Q4: 33,640 shares; 2026Q1: 33,640 shares 33,640$2.69M0.41%0Timeline
NBIXNEUROCRINE BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 13,334 shares; 2025Q2: 13,334 shares; 2025Q3: 18,117 shares; 2025Q4: 18,117 shares; 2026Q1: 18,117 shares 18,117$2.39M0.37%0Timeline
NUVBNUVATION BIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 772,652 shares; 2024Q4: 772,652 shares; 2025Q1: 772,652 shares; 2025Q2: 772,652 shares; 2025Q3: 1,020,547 shares; 2025Q4: 538,079 shares; 2026Q1: 508,846 shares 508,846$2.18M0.33%-29,233Timeline
CYTKCYTOKINETICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 32,195 shares 32,195$2.12M0.32%newTimeline
EHTHEHEALTH INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 2,347,519 shares; 2024Q4: 1,878,127 shares; 2025Q1: 1,684,336 shares; 2025Q2: 1,577,850 shares; 2025Q3: 1,544,619 shares; 2025Q4: 1,531,429 shares; 2026Q1: 1,482,797 shares 1,482,797$1.91M0.29%-48,632Timeline
CRSPCRISPR THERAPEUTICS AGQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 44,625 shares; 2025Q3: 41,226 shares; 2025Q4: 41,226 shares; 2026Q1: 39,605 shares 39,605$1.88M0.29%-1,621Timeline
BNTXBIONTECH SEQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 25,206 shares; 2024Q4: 25,206 shares; 2025Q1: 25,206 shares; 2025Q2: 25,206 shares; 2025Q3: 19,614 shares; 2025Q4: 19,614 shares; 2026Q1: 19,614 shares 19,614$1.74M0.27%0Timeline
PYXSPYXIS ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 170,000 shares; 2024Q4: 1,037,421 shares; 2025Q1: 1,037,421 shares; 2025Q2: 1,037,421 shares; 2025Q3: 1,037,421 shares; 2025Q4: 1,037,421 shares; 2026Q1: 1,010,510 shares 1,010,510$1.48M0.23%-26,911Timeline
VSTMVERASTEM INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 246,093 shares 246,093$1.3M0.2%newTimeline
BCYCBICYCLE THERAPEUTICS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 59,582 shares; 2024Q4: 248,934 shares; 2025Q1: 248,934 shares; 2025Q2: 248,934 shares; 2025Q3: 221,071 shares; 2025Q4: 221,071 shares; 2026Q1: 201,890 shares 201,890$937K0.14%-19,181Timeline
MDGLMADRIGAL PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 1,787 shares 1,787$935K0.14%newTimeline
HUMHUMANA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 3,985 shares; 2024Q4: 3,985 shares; 2025Q1: 3,985 shares; 2025Q2: 3,985 shares; 2025Q3: 3,985 shares; 2025Q4: 3,985 shares; 2026Q1: 3,985 shares 3,985$691K0.11%0Timeline
CMPSCOMPASS PATHWAYS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 115,616 shares; 2026Q1: 115,616 shares 115,616$639K0.1%0Timeline
XERSXERIS BIOPHARMA HOLDINGS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 104,410 shares 104,410$606K0.09%newTimeline
ABEOABEONA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 12,865 shares; 2024Q4: 108,865 shares; 2025Q1: 108,865 shares; 2025Q2: 108,865 shares; 2025Q3: 108,865 shares; 2025Q4: 108,865 shares; 2026Q1: 108,865 shares 108,865$488K0.07%0Timeline
INSPINSPIRE MED SYS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 8,772 shares; 2026Q1: 8,772 shares 8,772$452K0.07%0Timeline
URGNUROGEN PHARMA LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 24,500 shares; 2024Q4: 24,500 shares; 2025Q1: 24,500 shares; 2025Q2: 24,500 shares; 2025Q3: 24,500 shares; 2025Q4: 24,500 shares; 2026Q1: 24,500 shares 24,500$441K0.07%0Timeline
PRQRPROQR THRAPEUTICS N VQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 188,807 shares; 2025Q4: 188,807 shares; 2026Q1: 188,807 shares 188,807$306K0.05%0Timeline
ALDXALDEYRA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 225,465 shares; 2024Q4: 225,465 shares; 2025Q1: 225,465 shares; 2025Q2: 225,465 shares; 2025Q3: 225,465 shares; 2025Q4: 225,465 shares; 2026Q1: 155,709 shares 155,709$263K0.04%-69,756Timeline

Sold out in Q1 2026

Positions in the previous quarter's report that this quarter's report no longer lists.

SecurityShares beforeValue beforeType
GOSSGOSSAMER BIO INC4,471,592$13.9Mshares
GENERATION BIO COGENERATION BIO CO15,047$85.5Kshares
AKTXAKARI THERAPEUTICS PLC SPONSOR146,024$42.2Kshares

How Q1 2026 was built

Available 13F filings of this filer for the quarter and their roles: the base report is the latest original or restatement, NEW HOLDINGS amendments filed after it are added (method).

FilingRoleAmendmentFiledAcceptedIngested
13F-HR 0001306923-26-000004 base2026-05-15acceptance time not in the bulk data set