Institutional Manager · CIK 0001306923
Palo Alto Investors LP
PALO ALTO, CA · File #028-11013
Latest AUM
$718.4M
Positions
49
Top-10 Concentration
67.8%
Filings
9
Portfolio Value Over Time
2024-03
2024-06
2024-09
2024-12
2025-03
2025-06
2025-09
2025-12
Biggest QoQ Changes
Ranked by conviction flow (share change × current price) so mark-to-market moves don't dominate. Price effect column shows how much of the $ change was just the stock moving.
| Action | Issuer | Ticker / CUSIP | Δ Shares | Flow ($) | Price Effect |
|---|---|---|---|---|---|
| EXITED | ALNYLAM PHARMACEUTICALS INC | 02043Q107 | -32,320 | -$14.7M | $0 |
| NEW | COMPASS THERAPEUTICS INC | CMPX | +2,532,419 | +$13.6M | $0 |
| NEW | ANNEXON INC | ANNX | +2,384,192 | +$12.0M | $0 |
| ADD | DISC MEDICINE INC | IRON | +93,156 | +$7.4M | +$3.0M |
| ADD | MIRUM PHARMACEUTICALS INC | MIRM | +91,721 | +$7.2M | +$367,496 |
| NEW | CAPRICOR THERAPEUTICS INC | CAPR | +226,304 | +$6.5M | $0 |
| NEW | BICARA THERAPEUTICS INC | BCAX | +298,575 | +$5.0M | $0 |
| EXITED | AVIDITY BIOSCIENCES INC | 05370A108 | -109,831 | -$4.8M | $0 |
| NEW | XENON PHARMACEUTICALS INC | XENE | +96,519 | +$4.3M | $0 |
| REDUCE | NUVATION BIO INC | NUVB | -482,468 | -$4.3M | +$5.4M |
Sector Allocation
Filing History
- 13F HOLDINGS REPORTQ/E Dec 202549 pos · $718.4M
- 13F HOLDINGS REPORTQ/E Sep 202544 pos · $540.4M
- 13F HOLDINGS REPORTQ/E Jun 202545 pos · $470.0M
- 13F HOLDINGS REPORTQ/E Mar 202544 pos · $525.1M
- 13F HOLDINGS REPORTQ/E Dec 202443 pos · $645.4M
- 13F HOLDINGS REPORTQ/E Sep 202445 pos · $769.9M
- 13F HOLDINGS REPORTQ/E Jun 202439 pos · $863.0M
- 13F HOLDINGS REPORTQ/E Mar 202438 pos · $886.7M
- 13F HOLDINGS REPORTQ/E Dec 202329 pos · $1.06B
Top 20 Holdings — Dec 2025
| # | Issuer | Ticker | Shares | Value | % of Portfolio |
|---|---|---|---|---|---|
| 1 | INSMED INC | INSM | 489,482 | $85.2M | 11.86% |
| 2 | AMICUS THERAPEUTICS INC | FOLD | 5,205,767 | $74.1M | 10.32% |
| 3 | PTC THERAPEUTICS INC | PTCT | 903,916 | $68.7M | 9.56% |
| 4 | ACADIA PHARMACEUTICALS INC | ACAD | 2,484,031 | $66.3M | 9.24% |
| 5 | BIOMARIN PHARMACEUTICAL INC | BMRN | 746,256 | $44.3M | 6.17% |
| 6 | ANAPTYSBIO INC | ANABV | 690,032 | $33.5M | 4.66% |
| 7 | BIOGEN INC | BIIB | 183,571 | $32.3M | 4.50% |
| 8 | DYNE THERAPEUTICS INC | DYN | 1,472,197 | $28.8M | 4.01% |
| 9 | UNITED THERAPEUTICS CORP | UTHR | 58,186 | $28.4M | 3.95% |
| 10 | DISC MEDICINE INC | IRON | 317,456 | $25.2M | 3.51% |
| 11 | IOVANCE BIOTHERAPEUTICS INC | IOVA | 7,116,676 | $19.4M | 2.70% |
| 12 | NOVOCURE LTD | NVCR | 1,298,964 | $16.8M | 2.34% |
| 13 | SYNDAX PHARMACEUTICALS INC | SNDX | 794,507 | $16.7M | 2.32% |
| 14 | GOSSAMER BIO INC | GOSS | 4,471,592 | $13.9M | 1.93% |
| 15 | COMPASS THERAPEUTICS INC | CMPX | 2,532,419 | $13.6M | 1.89% |
| 16 | PROTHENA CORP PLC | PRTA | 1,320,510 | $12.6M | 1.76% |
| 17 | MIRUM PHARMACEUTICALS INC | MIRM | 156,421 | $12.4M | 1.72% |
| 18 | ANNEXON INC | ANNX | 2,384,192 | $12.0M | 1.67% |
| 19 | ULTRAGENYX PHARMACEUTICAL IN | RARE | 461,294 | $10.6M | 1.48% |
| 20 | DENALI THERAPEUTICS INC | DNLI | 641,239 | $10.6M | 1.47% |