Siren, L.L.C. — 13F Holdings & Portfolio
CIK 2005245 · latest 13F-HR filed 2026-08-13
Siren, L.L.C. manages $4.94B in 13F-reported U.S. long-equity assets across 119 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are SRRK (10.66%), KYMR (6.81%), ERAS (4.23%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 25 new positions, exited 10, added to 55, 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.
GREENWICH, CT 06831
$4.94B
Long-equity book
119
Distinct positions
2026-06-30
Filed 2026-08-13
+25 / −10 / ↑55 / ↓24
vs 2026-03-31
| Name | Title / Status | Ownership | Type |
|---|
Top Adds (vs prior quarter)
- Veradermics Inc$108.4M +114.1%
- Tango Therapeutics Inc$74.8M +63.2%
- Kymera Therapeutics Inc$71.2M +26.8%
- Rhythm Pharmaceuticals Inc$63.1M +99.9%
- Enliven Therapeutics Inc$60.8M +207.8%
Top Trims
- Structure Therapeutics Inc-$17.2M -26.8%
- Crinetics Pharmaceuticals Inc-$16.0M -23.1%
- Olema Pharmaceuticals Inc-$10.2M -14.3%
- Edgewise Therapeutics Inc-$10.2M -7.3%
- Dbv Technologies SA-$8.3M -21.5%
New Positions
- Parabilis Medicines Inc$81.9M
- Abivax SA$76.8M
- Hemab Therapeutics Holdings Inc$76.6M
- Relay Therapeutics Inc$68.3M
- Kailera Therapeutics Inc$48.8M
Exited Positions
- Centessa Pharmaceuticals PLC$41.8M
- enGene Holdings Inc$35.8M
- Fulcrum Therapeutics Inc$18.0M
- WAVE Life Sciences Ltd$17.8M
- Uniqure NV$16.4M
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 | Scholar Rock Holding Corp | SRRK | 80706P103 | $526.6M | 10.66% | 9,575,013 | SH |
| 2 | Kymera Therapeutics Inc | KYMR | 501575104 | $336.7M | 6.81% | 2,935,830 | SH |
| 3 | Erasca Inc | ERAS | 29479A108 | $208.8M | 4.23% | 11,397,781 | SH |
| 4 | Veradermics Inc | MANE | 922967104 | $203.5M | 4.12% | 1,655,374 | SH |
| 5 | Tango Therapeutics Inc | TNGX | 87583X109 | $193.2M | 3.91% | 6,179,364 | SH |
| 6 | Revolution Medicines Inc | RVMD | 76155X100 | $168.6M | 3.41% | 900,000 | SH |
| 7 | Bicara Therapeutics Inc | BCAX | 055477103 | $166.4M | 3.37% | 5,602,970 | SH |
| 8 | Arrowhead Pharmaceuticals Inc | ARWR | 04280A100 | $139.8M | 2.83% | 1,715,476 | SH |
| 9 | BeOne Medicines AG | ONC | 07725L102 | $132.5M | 2.68% | 465,000 | SH |
| 10 | Edgewise Therapeutics Inc | EWTX | 28036F105 | $129.4M | 2.62% | 3,184,629 | SH |
| 11 | Rhythm Pharmaceuticals Inc | RYTM | 76243J105 | $126.2M | 2.55% | 1,136,275 | SH |
| 12 | Lexicon Pharmaceuticals Inc | LXRX | 528872302 | $106.3M | 2.15% | 44,303,518 | SH |
| 13 | Enliven Therapeutics Inc | ELVN | 29337E102 | $90.1M | 1.82% | 1,774,411 | SH |
| 14 | Spyre Therapeutics Inc | SYRE | 00773J202 | $86.0M | 1.74% | 968,598 | SH |
| 15 | Parabilis Medicines Inc | PBLS | 698955101 | $81.9M | 1.66% | 2,992,259 | SH |
| 16 | Xenon Pharmaceuticals Inc | XENE | 98420N105 | $79.6M | 1.61% | 1,318,564 | SH |
| 17 | Solid Biosciences Inc | SLDB | 83422E204 | $76.8M | 1.55% | 7,690,405 | SH |
| 18 | Abivax SA | ABVX | 00370M103 | $76.8M | 1.55% | 576,000 | SH |
| 19 | Hemab Therapeutics Holdings Inc | COAG | 423494103 | $76.6M | 1.55% | 2,086,834 | SH |
| 20 | Cogent Biosciences Inc | COGT | 19240Q201 | $72.0M | 1.46% | 1,859,279 | SH |
| 21 | Relay Therapeutics Inc | RLAY | 75943R102 | $68.3M | 1.38% | 3,650,000 | SH |
| 22 | Taysha Gene Therapies Inc | TSHA | 877619106 | $67.1M | 1.36% | 9,846,579 | SH |
| 23 | Definium Therapeutics Inc | DFTX | 24477V105 | $66.8M | 1.35% | 1,419,493 | SH |
| 24 | Stoke Therapeutics Inc | STOK | 86150R107 | $65.3M | 1.32% | 1,995,347 | SH |
| 25 | Disc Medicine Inc | IRON | 254604101 | $65.0M | 1.31% | 888,401 | SH |
| 26 | Cytokinetics Inc | CYTK | 23282W605 | $64.7M | 1.31% | 758,952 | SH |
| 27 | Septerna Inc | SEPN | 81734D104 | $63.6M | 1.29% | 1,900,000 | SH |
| 28 | Olema Pharmaceuticals Inc | OLMA | 68062P106 | $60.8M | 1.23% | 4,856,949 | SH |
| 29 | Arcus Biosciences Inc | RCUS | 03969F109 | $53.8M | 1.09% | 1,745,000 | SH |
| 30 | Crinetics Pharmaceuticals Inc | CRNX | 22663K107 | $53.2M | 1.08% | 1,420,788 | SH |
| 31 | Kailera Therapeutics Inc | KLRA | 482931102 | $48.8M | 0.99% | 2,214,286 | SH |
| 32 | Dyne Therapeutics, Inc | DYN | 26818M108 | $47.3M | 0.96% | 2,129,125 | SH |
| 33 | Structure Therapeutics Inc | GPCR | 86366E106 | $46.9M | 0.95% | 872,967 | SH |
| 34 | Taboola.com Ltd | TBLA | M8744T106 | $42.1M | 0.85% | 8,423,410 | SH |
| 35 | Palvella Therapeutics Inc | PVLA | 697947109 | $39.3M | 0.80% | 257,485 | SH |
| 36 | Silence Therapeutics PLC | SLN | 82686Q101 | $36.4M | 0.74% | 3,311,438 | SH |
| 37 | Denali Therapeutics Inc | DNLI | 24823R105 | $35.9M | 0.73% | 1,396,513 | SH |
| 38 | Remitly Global Inc | RELY | 75960P104 | $34.6M | 0.70% | 1,543,271 | SH |
| 39 | Cullinan Therapeutics Inc | CGEM | 230031106 | $34.5M | 0.70% | 1,893,410 | SH |
| 40 | Capital One Finl Corp | COF | 14040H105 | $34.4M | 0.70% | 171,615 | SH |
| 41 | Trevi Therapeutics Inc | TRVI | 89532M101 | $33.3M | 0.67% | 1,786,867 | SH |
| 42 | Alphabet Inc | GOOGL | 02079K305 | $32.2M | 0.65% | 90,000 | SH |
| 43 | Dbv Technologies SA | DBVT | 23306J309 | $30.5M | 0.62% | 1,857,362 | SH |
| 44 | Absci Corp | ABSI | 00091E109 | $28.7M | 0.58% | 2,474,764 | SH |
| 45 | Sionna Therapeutics Inc | SION | 829401108 | $26.9M | 0.54% | 610,515 | SH |
| 46 | Rapport Therapeutics Inc | RAPP | 75383L102 | $26.7M | 0.54% | 641,469 | SH |
| 47 | Amylyx Pharmaceuticals Inc | AMLX | 03237H101 | $26.6M | 0.54% | 1,480,586 | SH |
| 48 | Annexon Inc | ANNX | 03589W102 | $25.5M | 0.52% | 4,458,646 | SH |
| 49 | Monopar Therapeutics Inc | MNPR | 61023L207 | $25.0M | 0.51% | 270,118 | SH |
| 50 | Oruka Therapeutics Inc | ORKA | 687604108 | $23.8M | 0.48% | 250,000 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-13 | $4.94B | 119 | 0002005245-26-000008 |
| 2026-03-31 | 2026-05-14 | $3.61B | 102 | 0002005245-26-000006 |
| 2025-12-31 | 2026-02-13 | $3.35B | 115 | 0002005245-26-000003 |
| 2025-09-30 | 2025-11-13 | $2.56B | 117 | 0002005245-25-000012 |