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Siren LLC’s Rhythm Pharmaceuticals RYTM Stock Holding History

Siren LLC’s Portfolio RYTM Stock Details RYTM Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$63.1M Buy
725,511
+225,536
+45% +$21.9M 1.75% 20
2025
Q4 		$53.5M Hold
499,975
– – 1.6% 21
2025
Q3 		$50.5M Buy
499,975
+90,233
+22% +$8.38M 1.98% 15
2025
Q2 		$25.9M Buy
409,742
+132,209
+48% +$8.1M 1.34% 20
2025
Q1 		$14.7M Buy
+277,533
New +$15.4M 0.83% 30

Other funds holding RYTM

RCM
RA Capital Management Boston, Massachusetts $9.44B AUM 157.3% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
BBA
Baker Bros. Advisors New York $17.4B AUM 131.5% 1-Year Est. Return
Primecap Management
Primecap Management Pasadena, California $127B AUM 44.11% 1-Year Est. Return
VPM
Vanguard Portfolio Management Malvern, Pennsylvania $1.91T AUM
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
PA
Perceptive Advisors New York $5.12B AUM 314.02% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return
Goldman Sachs
Goldman Sachs New York $871B AUM 31.28% 1-Year Est. Return
Westfield Capital Management
Westfield Capital Management Boston, Massachusetts $23.8B AUM 49.45% 1-Year Est. Return

Siren LLC's RYTM Position: Q1 2026 in Review

Siren LLC increased its Rhythm Pharmaceuticals (RYTM) stake by 45% in Q1 2026, buying an estimated $21.9M and bringing the position to 725,511 shares worth $63.1M. The position accounts for 1.75% of the portfolio, ranked #20.

Siren LLC first reported a position in RYTM in Q1 2025 and has held it in 5 quarters since. 285 funds tracked by Wall St. Rank hold RYTM as of Q1 2026.

  • Siren LLC held 725,511 shares of Rhythm Pharmaceuticals worth $63.1M as of Q1 2026.
  • Siren LLC bought 225,536 Rhythm Pharmaceuticals shares in Q1 2026, an estimated $21.9M.
  • Rhythm Pharmaceuticals made up 1.75% of Siren LLC's portfolio in Q1 2026, its #20 holding.
  • Siren LLC first reported a position in Rhythm Pharmaceuticals in Q1 2025 and has held it in 5 quarters since.
  • 285 funds tracked by Wall St. Rank held Rhythm Pharmaceuticals as of Q1 2026.

Based on Siren LLC's 13F filing for Q1 2026, filed 14 May 2026.