Stocks/Funds/CIK 2005245

Siren, L.L.C.

Quarterly 13F filings · Latest period 2026-03-31 · CIK 2005245
Assets
$3.61B
+103.5% YoY
Holdings
100
Lifetime alpha vs market
+26.91% annual
Average hold time
1.2 yr
median 1.5 yr

Quarterly history

Cum return +65% vs S&P +15% · α +50% lifetimeAUM $3.6B · peak $3.6BFlow $-5M (-0%)2024-092024-122025-032025-062025-092025-122026-03
AUM ($B)fundS&P 500(gap = α)/ Flow in/out

Behavior signals (lifetime)

Dip response
+7.10%
adds when stocks drop
when a holding falls −10%+
Middle response
-0.16%
baseline attrition
Rally response
-5.94%
trims into rallies
when a holding rises +10%+

Top positions · 30

Ticker$ value% portYoYHold time
SRRKScholar Rock Holding Cor$532M14.8%+52.9%1.8 yr
KYMRKymera Therapeutics, Inc$265M7.4%+204.3%1.8 yr
ERASErasca, Inc.$182M5.0%+1081.0%1.8 yr
EWTXEdgewise Therapeutics, I$140M3.9%+43.2%1.8 yr
ONCBeOne Medicines Ltd.$138M3.8%+9.1%1.8 yr
TNGXTango Therapeutics, Inc.$118M3.3%+1427.0%1.8 yr
BCAXBicara Therapeutics Inc.$115M3.2%+52.6%1.8 yr
RVMDRevolution Medicines, In$108M3.0%+175.0%1.8 yr
ARWRArrowhead Pharmaceutical$101M2.8%+392.2%1.8 yr
MANEVeradermics, Incorporate$95M2.6%0.3 yr
XENEXenon Pharmaceuticals In$77M2.1%+73.3%1.8 yr
OLMAOlema Pharmaceuticals, I$71M2.0%+296.5%0.5 yr
CRNXCrinetics Pharmaceutical$69M1.9%+8.3%1.8 yr
LXRXLexicon Pharmaceuticals,$69M1.9%+238.5%1.8 yr
COGTCogent Biosciences, Inc.$66M1.8%+542.6%1.0 yr

Portfolio composition (YoY)

Industry mix
Biotechnology83.6%+12.8pp$3.02B
Unknown5.3%-5.4pp$192M
Medical - Pharmaceuticals4.4%-3.7pp$160M
Internet Content & Information1.7%-0.7pp$62M
Software - Infrastructure1.5%-0.6pp$53M
Software - Application1.0%-1.1pp$38M
Semiconductors1.0%+0.2pp$36M
Specialty Retail0.5%-0.5pp$18M
Asset Management0.3%$9M
Auto - Manufacturers0.2%+0.1pp$8M
Country
US88.4%+11.2pp
Unknown5.3%-5.4pp
CA2.3%+0.9pp
GB1.8%-2.6pp
SG0.5%-1.2pp
NL0.5%-2.1pp
TW0.4%+0.1pp
RU0.3%+0.2pp
Top 5: 34.8% · Top 10: 49.8% · Top 25: 74.7%

Winners

TickerPrev $PnLYoY %
KYMR$89M+0.18B204.3%
SRRK$297M+0.16B52.9%
ARWR$34M+0.13B392.2%
ERAS$12M+0.13B1081.0%
CNTA$43M+0.08B176.2%

Losers

TickerPrev $PnLYoY %

Top buys this quarter · 15

MANE Veradermics, Incorporatednew+$95M
ERAS Erasca, Inc.+$40M
XENE Xenon Pharmaceuticals Inc.+$29M
ELVN Enliven Therapeutics, Inc.new+$29M
ORIC ORIC Pharmaceuticals, Inc.+$25M
DMRA Galecto, Inc.new+$23M
PVLA Palvella Therapeutics, Inc.+$23M
ANNX Annexon, Inc.new+$22M
OLMA Olema Pharmaceuticals, Inc.+$71M
RYTM Rhythm Pharmaceuticals, Inc.+$20M

Top sells this quarter · 15

CNTA Centessa Pharmaceuticals plc$118M
APLS Apellis Pharmaceuticals, Inc.exit$104M
TNGX Tango Therapeutics, Inc.$72M
DYN Dyne Therapeutics, Inc.$23M
RVMD Revolution Medicines, Inc.$106M
IHS IHS Holding Limitedexit$19M
MLYS Mineralys Therapeutics, Inc.exit$19M
ALMS Alumis Inc. Common Stockexit$11M
ONC BeOne Medicines Ltd.$10M
KYMR Kymera Therapeutics, Inc.$256M

Quarterly history (TTM returns)

PeriodAUM# PosReturn (1yr)SPY (1yr)Alpha (1yr)Flow
2026-03-31$3.61B100+92.44%+17.59%+74.85%-0.01B
2025-12-31$3.35B113+35.24%+17.72%+17.53%+0.15B
2025-09-30$2.56B115+22.36%+17.52%+4.84%+0.01B
2025-06-30$1.93B110+8.49%+10.78%-2.29%+0.01B
2025-03-31$1.77B116-24.27%-4.27%-20.00%+0.06B
2024-12-31$2.26B117+13.18%+2.49%+10.69%+0.00B
2024-09-30$2.00B109