Siren, L.L.C.
Reported holdings as of Q2 2026, from 8 quarterly filings.
This filer last reported in Q2 2026; the most recent quarter on file across all filers is Q3 2026. Firms that restructure stop filing under one CIK and start under another, so a successor entity may hold these positions now under a similar name.
Holdings
Download these holdings as CSV
| Security | Ticker | Value | Shares | Weight | Weight change | Held | Change |
|---|---|---|---|---|---|---|---|
| SCHOLAR ROCK HLDG CORP | SRRK | $526.6M | 9,575,013 | -4.09pp | 8q | -11.5%-$68.8M | |
| KYMERA THERAPEUTICS INC | KYMR | $336.7M | 2,935,830 | -0.55pp | 8q | -7.9%-$28.8M | |
| ERASCA INC | ERAS | $208.8M | 11,397,781 | -0.82pp | 8q | +1.4%+$2.8M | |
| VERADERMICS INC | MANE | $203.5M | 1,655,374 | +1.48pp | 2q | +10.0%+$18.4M | |
| TANGO THERAPEUTICS INC | TNGX | $193.2M | 6,179,364 | +0.63pp | 8q | +9.2%+$16.3M | |
| REVOLUTION MEDICINES INC | RVMD | $168.6M | 900,000 | +0.42pp | 8q | -19.0%-$39.5M | |
| BICARA THERAPEUTICS INC | BCAX | $166.4M | 5,602,970 | +0.17pp | 8q | -3.4%-$5.9M | |
| ARROWHEAD PHARMACEUTICALS IN | ARWR | $139.8M | 1,715,476 | +0.02pp | 8q | +6.2%+$8.2M | |
| BEONE MEDICINES LTD | ONC | $132.5M | 465,000 | -1.15pp | 8q | HELD | |
| EDGEWISE THERAPEUTICS INC | EWTX | $129.4M | 3,184,629 | -1.25pp | 8q | -28.1%-$50.6M | |
| RHYTHM PHARMACEUTICALS INC | RYTM | $126.2M | 1,136,275 | +0.80pp | 6q | +56.6%+$45.6M | |
| LEXICON PHARMACEUTICALS INC | LXRX | $106.3M | 44,303,518 | +0.24pp | 8q | HELD | |
| ENLIVEN THERAPEUTICS INC | ELVN | $90.1M | 1,774,411 | +1.01pp | 2q | +137.8%+$52.2M | |
| SPYRE THERAPEUTICS INC | SYRE | $86.0M | 968,598 | +0.60pp | 7q | +18.3%+$13.3M | |
| PARABILIS MEDICINES INC | PBLS | $81.9M | 2,992,259 | - | new | NEW | |
| XENON PHARMACEUTICALS INC | XENE | $79.6M | 1,318,564 | -0.51pp | 8q | HELD | |
| SOLID BIOSCIENCES INC | SLDB | $76.8M | 7,690,405 | +0.02pp | 8q | HELD | |
| ABIVAX SA | ABVX | $76.8M | 576,000 | - | new | NEW | |
| HEMAB THERAPEUTICS HLDGS INC | $76.6M | 2,086,834 | - | new | NEW | ||
| ARCUS BIOSCIENCES INC | RCUS | $74.6M | 2,420,430 | -0.29pp | 8q | -19.5%-$18.1M | |
| COGENT BIOSCIENCES INC | COGT | $72.0M | 1,859,279 | -0.37pp | 5q | +8.8%+$5.8M | |
| RELAY THERAPEUTICS INC | RLAY | $68.3M | 3,650,000 | - | new | NEW | |
| TAYSHA GENE THERAPIES INC | TSHA | $67.1M | 9,846,579 | +0.26pp | 8q | +11.5%+$6.9M | |
| DEFINIUM THERAPEUTICS INC | DFTX | $66.8M | 1,419,493 | +0.87pp | 2q | +54.4%+$23.5M | |
| STOKE THERAPEUTICS INC | STOK | $65.3M | 1,995,347 | -0.48pp | 7q | HELD | |
| DISC MEDICINE INC | IRON | $65.0M | 888,401 | -0.44pp | 6q | -10.1%-$7.3M | |
| CYTOKINETICS INC | CYTK | $64.7M | 758,952 | +0.19pp | 2q | +23.6%+$12.4M | |
| SEPTERNA INC | SEPN | $63.6M | 1,900,000 | -0.04pp | 7q | -5.0%-$3.3M | |
| OLEMA PHARMACEUTICALS INC | OLMA | $60.8M | 4,856,949 | -0.74pp | 3q | +2.1%+$1.3M | |
| CRINETICS PHARMACEUTICALS IN | CRNX | $53.2M | 1,420,788 | -0.84pp | 8q | -25.4%-$18.1M | |
| KAILERA THERAPEUTICS INC | KLRA | $48.8M | 2,214,286 | - | new | NEW | |
| DYNE THERAPEUTICS INC | DYN | $47.3M | 2,129,125 | -0.16pp | 8q | -4.5%-$2.2M | |
| STRUCTURE THERAPEUTICS INC | GPCR | $46.9M | 872,967 | -0.83pp | 4q | -34.3%-$24.5M | |
| TABOOLA.COM LTD | TBLA | $42.1M | 8,423,410 | flat | 8q | -15.5%-$7.7M | |
| PALVELLA THERAPEUTICS INC NE | PVLA | $39.3M | 257,485 | -0.09pp | 3q | HELD | |
| SILENCE THERAPEUTICS PLC | SLN | $36.4M | 3,311,438 | +0.31pp | 8q | +13.7%+$4.4M | |
| DENALI THERAPEUTICS INC | DNLI | $35.9M | 1,396,513 | -0.02pp | 8q | HELD | |
| REMITLY GLOBAL INC | RELY | $34.6M | 1,543,271 | +0.03pp | 8q | HELD | |
| CULLINAN THERAPEUTICS INC | CGEM | $34.5M | 1,893,410 | +0.23pp | 8q | +58.7%+$12.7M | |
| CAPITAL ONE FINL CORP | COF | $34.4M | 171,615 | - | new | NEW | |
| TREVI THERAPEUTICS INC | TRVI | $33.3M | 1,786,867 | +0.08pp | 7q | HELD | |
| ORIC PHARMACEUTICALS INC | ORIC | $32.5M | 2,998,192 | -0.40pp | 8q | HELD | |
| ALPHABET INC | GOOGL | $32.2M | 90,000 | +0.13pp | 8q | +37.0%+$8.7M | |
| DBV TECHNOLOGIES S A | DBVT | $30.5M | 1,857,362 | -0.46pp | 3q | HELD | |
| ABSCI CORPORATION | ABSI | $28.7M | 2,474,764 | +0.43pp | 2q | +37.5%+$7.8M | |
| SIONNA THERAPEUTICS INC | SION | $26.9M | 610,515 | +0.21pp | 6q | +103.5%+$13.7M | |
| RAPPORT THERAPEUTICS INC | RAPP | $26.7M | 641,469 | -0.02pp | 8q | HELD | |
| AMYLYX PHARMACEUTICALS INC | AMLX | $26.6M | 1,480,586 | +0.06pp | 2q | +20.4%+$4.5M | |
| ANNEXON INC | ANNX | $25.5M | 4,458,646 | -0.09pp | 2q | +12.6%+$2.9M | |
| MONOPAR THERAPEUTICS INC | MNPR | $25.0M | 270,118 | +0.10pp | 3q | HELD | |
| ORUKA THERAPEUTICS INC | ORKA | $23.8M | 250,000 | - | new | NEW | |
| SEAPORT THERAPEUTICS INC | SPTX | $23.8M | 1,095,316 | - | new | NEW | |
| DAMORA THERAPEUTICS INC | DMRA | $23.4M | 900,000 | -0.17pp | 2q | HELD | |
| TYRA BIOSCIENCES INC | TYRA | $23.2M | 725,000 | - | new | NEW | |
| MICROSOFT CORP CALL | MSFT | $22.9M | 37,500 | +0.04pp | 8q | -9.4%-$2.4M | |
| ZURA BIO LTD | ZURA | $22.0M | 3,734,866 | -0.17pp | 3q | HELD | |
| TAIWAN SEMICONDUCTOR MANUFAC | TSM | $21.3M | 44,700 | +0.04pp | 8q | +5.9%+$1.2M | |
| NVIDIA CORPORATION | NVDA | $19.0M | 95,000 | -0.05pp | 8q | +6.6%+$1.2M | |
| REZOLUTE INC | RZLT | $17.3M | 3,328,287 | +0.07pp | 2q | HELD | |
| MAPLIGHT THERAPEUTICS INC | MPLT | $16.1M | 450,000 | +0.07pp | 3q | HELD | |
| NEUMORA THERAPEUTICS INC. | NMRA | $14.4M | 8,497,822 | -0.17pp | 8q | HELD | |
| NEBIUS GROUP N.V. | NBIS | $14.4M | 52,000 | -0.04pp | 7q | -54.2%-$17.0M | |
| CYTOMX THERAPEUTICS INC | CTMX | $13.0M | 3,457,711 | -0.19pp | 2q | HELD | |
| GENERATE BIOMEDICINES INC | GENB | $12.4M | 736,104 | flat | 2q | HELD | |
| INHIBIKASE THERAPEUTICS INC | IKT | $11.9M | 5,850,000 | -0.03pp | 3q | HELD | |
| ADAGENE INC | ADAG | $11.2M | 2,666,666 | - | new | NEW | |
| Engene Therapeutics Inc | ENGN | $10.8M | 6,256,662 | - | new | NEW | |
| WHITEHAWK THERAPEUTICS INC | WHWK | $10.7M | 2,337,102 | +0.02pp | 6q | +12.3%+$1.2M | |
| DATADOG INC | DDOG | $10.4M | 40,000 | +0.03pp | 8q | -26.3%-$3.7M | |
| SERVICENOW INC | NOW | $9.9M | 100,000 | -0.05pp | 8q | +14.8%+$1.3M | |
| BROADCOM INC | AVGO | $9.4M | 25,000 | +0.06pp | 3q | +66.7%+$3.8M | |
| IONQ INC | IONQ | $9.1M | 170,000 | +0.05pp | 8q | HELD | |
| JFROG LTD | FROG | $8.7M | 95,500 | +0.01pp | 8q | -25.9%-$3.0M | |
| OCULIS HOLDING AG | OCS | $8.7M | 625,000 | - | new | NEW | |
| IREN LIMITED | IREN | $8.0M | 175,000 | +0.12pp | 4q | +306.0%+$6.0M | |
| AMAZON COM INC | AMZN | $7.7M | 32,500 | -0.11pp | 8q | -30.3%-$3.4M | |
| CROWDSTRIKE HLDGS INC | CRWD | $7.6M | 10,000 | -0.10pp | 8q | -56.7%-$10.0M | |
| DESIGN THERAPEUTICS INC | DSGN | $7.6M | 523,212 | - | new | NEW | |
| PDD HOLDINGS INC | PDD | $7.2M | 95,000 | -0.09pp | 8q | +13.9%+$884.8K | |
| SATELLOS BIOSCIENCE INC | MSLE | $6.9M | 892,074 | flat | 2q | HELD | |
| DYNATRACE INC | DT | $6.8M | 155,000 | -0.02pp | 8q | +3.3%+$219.5K | |
| APPLE INC CALL | AAPL | $6.7M | options only | - | new | OPTIONS | |
| TENAX THERAPEUTICS INC | TENX | $6.2M | 427,141 | -0.06pp | 4q | HELD | |
| VTV THERAPEUTICS INC | VTVT | $6.1M | 163,000 | -0.06pp | 4q | HELD | |
| ELOXX PHARMACEUTICALS INC | $5.6M | 400,000 | - | new | NEW | ||
| AGOMAB THERAPEUTICS NV | AGMB | $5.3M | 411,250 | -0.01pp | 2q | HELD | |
| ALIBABA GROUP HLDG LTD | BABA | $4.8M | 50,000 | - | new | NEW | |
| KORRO BIO INC | KRRO | $4.6M | 347,718 | -0.02pp | 8q | HELD | |
| CELLEBRITE DI LTD | CLBT | $4.5M | 311,544 | -0.03pp | 5q | HELD | |
| INVIVYD INC | IVVD | $4.4M | 5,000,000 | -0.06pp | 3q | +25.0%+$872.4K | |
| OUSTER INC | OUST | $4.2M | 67,500 | - | new | NEW | |
| PALISADE BIO INC | PALI | $4.2M | 2,000,000 | - | new | NEW | |
| AEVA TECHNOLOGIES INC | AEVA | $4.2M | 145,459 | +0.04pp | 2q | +32.2%+$1.0M | |
| SEER INC | SEER | $4.1M | 2,458,673 | -0.03pp | 8q | HELD | |
| NOVABRIDGE BIOSCIENCES | NBP | $3.9M | 2,004,739 | -0.13pp | 4q | -33.2%-$1.9M | |
| GITLAB INC | GTLB | $3.8M | 125,000 | +0.02pp | 5q | +25.0%+$763.2K | |
| ODYSSEY THERAPEUTICS INC | ODTX | $3.7M | 200,000 | - | new | NEW | |
| FOGHORN THERAPEUTICS INC | FHTX | $3.5M | 720,720 | -0.02pp | 8q | HELD | |
| AGENUS INC | AGEN | $3.3M | 1,064,250 | -0.03pp | 6q | HELD | |
| MONDAY COM LTD | MNDY | $3.1M | 42,500 | +0.01pp | 4q | +70.0%+$1.3M | |
| ZOETIS INC | ZTS | $2.5M | 35,000 | - | new | NEW | |
| WORKIVA INC | WK | $2.2M | 45,000 | -0.11pp | 7q | -51.4%-$2.3M | |
| NETFLIX INC | NFLX | $1.8M | 25,000 | - | new | NEW | |
| KALARIS THERAPEUTICS INC | KLRS | $1.8M | 435,798 | -0.03pp | 6q | HELD | |
| QUANTINUUM INC | QNT | $1.6M | 20,000 | - | new | NEW | |
| RANI THERAPEUTICS HLDGS INC | RANI | $1.5M | 2,000,000 | -0.01pp | 3q | HELD | |
| TESLA INC | TSLA | $1.5M | 3,500 | -0.19pp | 6q | -83.7%-$7.6M | |
| KE HLDGS INC | BEKE | $1.5M | 100,000 | -0.01pp | 8q | HELD | |
| ENTERA BIO LTD | ENTX | $1.3M | 736,457 | - | new | NEW | |
| MEDLINE INC | MDLN | $986.0K | 25,000 | -0.01pp | 3q | HELD | |
| LUMENTUM HLDGS INC | LITE | $905.3K | 1,055 | - | new | NEW | |
| FIGMA INC | FIG | $904.5K | 50,000 | -0.01pp | 4q | HELD | |
| GOSSAMER BIO INC | GOSS | $857.4K | 5,208,968 | -0.03pp | 8q | HELD | |
| FOX CORP | FOXA | $521.6K | 10,000 | - | new | NEW | |
| AT&T INC | T | $517.5K | 25,000 | - | new | NEW | |
| NU HLDGS LTD | NU | $334.0K | 25,000 | flat | 2q | HELD |
By sector
Industry comes from the SIC code on each company's own SEC filings, which is self-reported and sometimes out of date. Derivative exposure is counted with the shares. Securities the SEC assigns no industry - funds, trusts, foreign issues - are shown as not classified rather than dropped.
| Sector | Value | Share |
|---|---|---|
| Biotech & Pharma | $4.4B | 88.1% |
| Software & IT Services | $178.6M | 3.6% |
| Other sectors | $169.6M | 3.4% |
| Not classified | $242.0M | 4.9% |
What the disclosed book did
This is not the fund's return. A 13F shows long US equity positions only, so shorts, bonds, foreign listings, private holdings and cash are all invisible here. What this measures is the quarter's change in value of the positions this manager disclosed, had they been left untouched - the return a reader following the filing would have earned.
| Quarter | Book | Market | Difference | Priced |
|---|---|---|---|---|
| Q2 2026 | +27.4% | +14.8% | +12.6% | 99% |
| Q1 2026 | +8.1% | -4.6% | +12.7% | 98% |
| Q4 2025 | +22.5% | +2.4% | +20.2% | 100% |
| Q3 2025 | +30.0% | +7.8% | +22.1% | 100% |
| Q2 2025 | +11.2% | +10.5% | +0.7% | 100% |
| Q1 2025 | -21.9% | -4.6% | -17.3% | 100% |
| Q4 2024 | +5.9% | +2.1% | +3.7% | 98% |
Market is SPY over the same two quarter ends, priced the same way as everything else here - the median across every filer reporting it. It is a large-cap US proxy, so a manager holding small caps or biotech will beat or trail it for reasons that are not skill. Prices are quarter-end to quarter-end and say nothing about the path in between, or about trades opened and closed inside a quarter.
Quarter by quarter
| Quarter | Value | Positions | New | Added | Trimmed | Exited | Top 10 | Days to file |
|---|---|---|---|---|---|---|---|---|
| Q2 2026 | $4.9B | 116 | 26 | 31 | 21 | 10 | 44.6% | 44 |
| Q1 2026 | $3.6B | 100 | 19 | 35 | 18 | 32 | 49.8% | 44 |
| Q4 2025 | $3.4B | 113 | 26 | 30 | 23 | 28 | 46.3% | 44 |
| Q3 2025 | $2.6B | 115 | 24 | 24 | 14 | 19 | 47.4% | 44 |
| Q2 2025 | $1.9B | 110 | 15 | 21 | 19 | 21 | 48.5% | 44 |
| Q1 2025 | $1.8B | 116 | 24 | 28 | 38 | 25 | 50.4% | 53 |
| Q4 2024 | $2.3B | 117 | 22 | 22 | 21 | 15 | 48.5% | 45 |
| Q3 2024 | $2.0B | 110 | 0 | 0 | 0 | 0 | 41.3% | 44 |
Rows marked UNVERIFIED ID, PLACEHOLDER ID, TICKER AS ID or NON-CUSIP ID carry an identifier that is not a valid CUSIP. They are shown because the filer reported that money, but treat the security named with caution - hover the chip for what is wrong with it, and see the methodology.
Held counts consecutive filings in which this manager reported the position, and can reach further back than the quarters listed above: the tabs begin at Q4 2018 because earlier coverage is too sparse to describe a market, but tenure is counted over every filing we hold, some reaching to 2007. A position sold and later rebought starts again from one.
Weight change is the shift in this position's share of the whole book, in percentage points. It is the more useful column: when money flows into or out of a broad fund, almost every holding is bought or sold at once, so added and trimmed largely track flows. A weight that rose while the book shrank is a decision. Both compare with the previous quarter this filer reported, not the previous calendar quarter.