Primecap Management
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Primecap Management’s Rhythm Pharmaceuticals RYTM Stock Holding History

Primecap Management’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 		$297M Sell
3,417,509
-61,160
-2% -$5.95M 0.23% 84
2025
Q4 		$372M Sell
3,478,669
-784,190
-18% -$83.2M 0.28% 74
2025
Q3 		$431M Sell
4,262,859
-615,178
-13% -$57.1M 0.33% 63
2025
Q2 		$308M Sell
4,878,037
-909,285
-16% -$55.7M 0.24% 79
2025
Q1 		$307M Sell
5,787,322
-783,868
-12% -$43.5M 0.25% 80
2024
Q4 		$368M Sell
6,571,190
-645,721
-9% -$35.7M 0.28% 73
2024
Q3 		$378M Sell
7,216,911
-95,480
-1% -$4.58M 0.28% 75
2024
Q2 		$300M Sell
7,312,391
-435,200
-6% -$17.4M 0.22% 82
2024
Q1 		$336M Sell
7,747,591
-305,057
-4% -$13.4M 0.25% 75
2023
Q4 		$370M Sell
8,052,648
-214,773
-3% -$6.78M 0.29% 72
2023
Q3 		$190M Sell
8,267,421
-31,896
-0.4% -$714K 0.16% 98
2023
Q2 		$137M Buy
8,299,317
+692,006
+9% +$12.5M 0.11% 116
2023
Q1 		$136M Buy
7,607,311
+696,169
+10% +$17.5M 0.12% 119
2022
Q4 		$201M Sell
6,911,142
-115,750
-2% -$2.97M 0.18% 97
2022
Q3 		$172M Buy
7,026,892
+662,798
+10% +$12.3M 0.17% 103
2022
Q2 		$26.4M Buy
6,364,094
+72,103
+1% +$395K 0.02% 201
2022
Q1 		$72.5M Buy
6,291,991
+35,000
+0.6% +$307K 0.05% 167
2021
Q4 		$62.4M Buy
6,256,991
+75,900
+1% +$853K 0.04% 183
2021
Q3 		$80.7M Buy
6,181,091
+27,400
+0.4% +$418K 0.06% 168
2021
Q2 		$120M Buy
6,153,691
+148,098
+2% +$3.08M 0.08% 147
2021
Q1 		$128M Buy
6,005,593
+1,663,102
+38% +$48.2M 0.09% 138
2020
Q4 		$129M Buy
4,342,491
+767,800
+21% +$19.5M 0.1% 138
2020
Q3 		$77.5M Buy
3,574,691
+29,900
+0.8% +$685K 0.06% 150
2020
Q2 		$79M Buy
3,544,791
+2,200
+0.1% +$42.9K 0.07% 152
2020
Q1 		$53.9M Buy
3,542,591
+1,448,900
+69% +$25.9M 0.05% 153
2019
Q4 		$48.1M Buy
2,093,691
+1,846,714
+748% +$41M 0.03% 174
2019
Q3 		$5.33M Buy
+246,977
New +$5.3M ﹤0.01% 247

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
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
Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return

Primecap Management's RYTM Position: Q1 2026 in Review

Primecap Management reduced its Rhythm Pharmaceuticals (RYTM) stake by 1.8% in Q1 2026, selling an estimated $5.95M and leaving 3,417,509 shares worth $297M. The position accounts for 0.23% of the portfolio, ranked #84.

Primecap Management first reported a position in RYTM in Q3 2019 and has held it in 27 quarters since. The position peaked at $431M in Q3 2025. 285 funds tracked by Wall St. Rank hold RYTM as of Q1 2026.

  • Primecap Management held 3,417,509 shares of Rhythm Pharmaceuticals worth $297M as of Q1 2026.
  • Primecap Management sold 61,160 Rhythm Pharmaceuticals shares in Q1 2026, an estimated $5.95M.
  • Rhythm Pharmaceuticals made up 0.23% of Primecap Management's portfolio in Q1 2026, its #84 holding.
  • Primecap Management first reported a position in Rhythm Pharmaceuticals in Q3 2019 and has held it in 27 quarters since.
  • Primecap Management's Rhythm Pharmaceuticals position peaked at $431M in Q3 2025.
  • 285 funds tracked by Wall St. Rank held Rhythm Pharmaceuticals as of Q1 2026.

Based on Primecap Management's 13F filing for Q1 2026, filed 11 May 2026.