Siren, L.L.C. — 13F Holdings & Portfolio
CIK 2005245 · latest 13F-HR filed 2026-05-14
Siren, L.L.C. manages $3.61B in 13F-reported U.S. long-equity assets across 102 reported positions as of its 2026-03-31 13F-HR filing. Its largest disclosed positions are SRRK (14.75%), KYMR (7.36%), ERAS (5.04%). Quarter over quarter (versus its 2025-12-31 filing) the fund opened 19 new positions, exited 32, added to 40, and trimmed 34.
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.
$3.61B
Long-equity book
102
Distinct positions
2026-03-31
Filed 2026-05-14
+19 / −32 / ↑40 / ↓34
vs 2025-12-31
| Name | Title / Status | Ownership | Type |
|---|
Top Adds (vs prior quarter)
- Erasca Inc$149.4M +458.5%
- Scholar Rock Holding Corp$55.3M +11.6%
- Tango Therapeutics Inc$46.0M +63.6%
- Xenon Pharmaceuticals Inc$40.2M +110.5%
- Oric Pharmaceuticals Inc$29.7M +360.9%
Top Trims
- Centessa Pharmaceuticals PLC-$58.9M -58.5%
- Dyne Therapeutics, Inc-$28.1M -41.0%
- WAVE Life Sciences Ltd-$23.9M -57.4%
- Taysha Gene Therapies Inc-$16.2M -29.2%
- Disc Medicine Inc-$15.3M -19.5%
New Positions
- Veradermics Inc$95.1M
- Cytokinetics Inc$40.5M
- Enliven Therapeutics Inc$29.3M
- Damora Therapeutics Inc$23.3M
- Annexon Inc$21.9M
Exited Positions
- Apellis Pharmaceuticals Inc$64.8M
- Ascendis Pharma A/S$50.3M
- RAPT Therapeutics Inc$46.6M
- Zymeworks Inc$44.2M
- Mineralys Therapeutics Inc$25.4M
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 | $532.2M | 14.75% | 10,825,013 | SH |
| 2 | Kymera Therapeutics Inc | KYMR | 501575104 | $265.4M | 7.36% | 3,186,830 | SH |
| 3 | Erasca Inc | ERAS | 29479A108 | $181.9M | 5.04% | 11,244,246 | SH |
| 4 | Edgewise Therapeutics Inc | EWTX | 28036F105 | $139.6M | 3.87% | 4,430,263 | SH |
| 5 | BeOne Medicines AG | ONC | 07725L102 | $138.1M | 3.83% | 465,000 | SH |
| 6 | Tango Therapeutics Inc | TNGX | 87583X109 | $118.3M | 3.28% | 5,657,105 | SH |
| 7 | Bicara Therapeutics Inc | BCAX | 055477103 | $115.4M | 3.20% | 5,802,970 | SH |
| 8 | Revolution Medicines Inc | RVMD | 76155X100 | $108.0M | 3.00% | 1,110,980 | SH |
| 9 | Arrowhead Pharmaceuticals Inc | ARWR | 04280A100 | $101.3M | 2.81% | 1,615,476 | SH |
| 10 | Veradermics Inc | MANE | 922967104 | $95.1M | 2.64% | 1,505,374 | SH |
| 11 | Xenon Pharmaceuticals Inc | XENE | 98420N105 | $76.7M | 2.13% | 1,318,564 | SH |
| 12 | Olema Pharmaceuticals Inc | OLMA | 68062P106 | $70.9M | 1.97% | 4,756,949 | SH |
| 13 | Crinetics Pharmaceuticals Inc | CRNX | 22663K107 | $69.1M | 1.92% | 1,903,636 | SH |
| 14 | Lexicon Pharmaceuticals Inc | LXRX | 528872302 | $69.1M | 1.92% | 44,303,518 | SH |
| 15 | Cogent Biosciences Inc | COGT | 19240Q201 | $65.8M | 1.82% | 1,709,279 | SH |
| 16 | Stoke Therapeutics Inc | STOK | 86150R107 | $65.0M | 1.80% | 1,995,347 | SH |
| 17 | Structure Therapeutics Inc | GPCR | 86366E106 | $64.0M | 1.78% | 1,328,698 | SH |
| 18 | Disc Medicine Inc | IRON | 254604101 | $63.2M | 1.75% | 988,401 | SH |
| 19 | Rhythm Pharmaceuticals Inc | RYTM | 76243J105 | $63.1M | 1.75% | 725,511 | SH |
| 20 | Solid Biosciences Inc | SLDB | 83422E204 | $55.4M | 1.53% | 7,690,405 | SH |
| 21 | Septerna Inc | SEPN | 81734D104 | $48.1M | 1.33% | 2,000,000 | SH |
| 22 | Centessa Pharmaceuticals PLC | CNTA | 152309100 | $41.8M | 1.16% | 1,053,464 | SH |
| 23 | Spyre Therapeutics Inc | SYRE | 00773J202 | $41.3M | 1.14% | 818,598 | SH |
| 24 | Cytokinetics Inc | CYTK | 23282W605 | $40.5M | 1.12% | 613,952 | SH |
| 25 | Dyne Therapeutics, Inc | DYN | 26818M108 | $40.4M | 1.12% | 2,229,125 | SH |
| 26 | Taysha Gene Therapies Inc | TSHA | 877619106 | $39.5M | 1.09% | 8,829,913 | SH |
| 27 | Dbv Technologies SA | DBVT | 23306J309 | $38.8M | 1.08% | 1,857,362 | SH |
| 28 | enGene Holdings Inc | ENGNW | 29286M105 | $35.8M | 0.99% | 5,253,159 | SH |
| 29 | Arcus Biosciences Inc | RCUS | 03969F109 | $34.8M | 0.97% | 1,612,077 | SH |
| 30 | Palvella Therapeutics Inc | PVLA | 697947109 | $32.1M | 0.89% | 257,485 | SH |
| 31 | Taboola.com Ltd | TBLA | M8744T106 | $30.9M | 0.86% | 9,969,495 | SH |
| 32 | Arcus Biosciences Inc | RCUS | 03969F109 | $30.1M | 0.84% | 1,395,000 | SH |
| 33 | Enliven Therapeutics Inc | ELVN | 29337E102 | $29.3M | 0.81% | 746,226 | SH |
| 34 | Denali Therapeutics Inc | DNLI | 24823R105 | $26.8M | 0.74% | 1,396,513 | SH |
| 35 | Oric Pharmaceuticals Inc | ORIC | 68622P109 | $25.2M | 0.70% | 1,990,617 | SH |
| 36 | Remitly Global Inc | RELY | 75960P104 | $24.2M | 0.67% | 1,543,271 | SH |
| 37 | Damora Therapeutics Inc | DMRA | 36322Q206 | $23.3M | 0.65% | 900,000 | SH |
| 38 | Zura Bio Ltd | ZURA | G9TY5A101 | $22.2M | 0.62% | 3,734,866 | SH |
| 39 | Annexon Inc | ANNX | 03589W102 | $21.9M | 0.61% | 3,958,646 | SH |
| 40 | Trevi Therapeutics Inc | TRVI | 89532M101 | $21.3M | 0.59% | 1,786,867 | SH |
| 41 | Rapport Therapeutics Inc | RAPP | 75383L102 | $20.1M | 0.56% | 641,469 | SH |
| 42 | Alphabet Inc | GOOGL | 02079K305 | $18.9M | 0.52% | 65,703 | SH |
| 43 | Fulcrum Therapeutics Inc | FULC | 359616109 | $18.0M | 0.50% | 2,350,000 | SH |
| 44 | WAVE Life Sciences Ltd | WVE | Y95308105 | $17.8M | 0.49% | 2,450,000 | SH |
| 45 | Definium Therapeutics Inc | DFTX | 24477V105 | $17.4M | 0.48% | 919,493 | SH |
| 46 | Amylyx Pharmaceuticals Inc | AMLX | 03237H101 | $17.1M | 0.47% | 1,230,000 | SH |
| 47 | Cullinan Therapeutics Inc | CGEM | 230031106 | $17.0M | 0.47% | 1,193,410 | SH |
| 48 | Neumora Therapeutics Inc | NMRA | 640979100 | $16.6M | 0.46% | 8,497,822 | SH |
| 49 | Uniqure NV | QURE | N90064101 | $16.4M | 0.45% | 1,000,000 | SH |
| 50 | CytomX Therapeutics Inc | CTMX | 23284F105 | $16.3M | 0.45% | 3,457,711 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 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 |