Rock Springs Capital Management LP

Hedge Fund • Sector

Rock Springs Capital Management LP is a Sector-focused Hedge Fund based in Baltimore, MD led by Nnamdi C Etoh, reporting $3.3B in AUM as of Q3 2025 with 82% Healthcare concentration.

CFONnamdi C Etoh

Portfolio Value: $1.7B
Positions: 91
Top Holding: ARGX at 6.18%
Last Reported: Q3 2025

Address650 S. Exeter Street, Suite 1070, Baltimore, MD, 21202, United States

Top Holdings

Largest long holdings in Rock Springs Capital Management LP's portfolio (37.9% of total portfolio)

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GthenH

Holding	Sector	Position	Weight	Traded	Ownership	Owned Since
1 ARGX argenx ARGX	Unknown Unknown	$105.3M	6.18%	-$24.3M Sold	— 142.8K shares	Q1 2025 Held for 8 months
2 Eli Lilly LLY	Drug Manufacturers - General Healthcare	$80.4M	4.72%	-$8.5M Sold	0.01% 105.4K shares	Q4 2023 Held for 1y 11m
3 Rhythm Pharmaceuticals, Inc. RYTM	Biotechnology Healthcare	$72.4M	4.25%	-$14.5M Sold	1.08% 717.1K shares	Q4 2017 Held for 7y 11m
4 Madrigal Pharmaceuticals, Inc. MDGL	Biotechnology Healthcare	$63.2M	3.71%	-$1.2M Sold	0.62% 137.7K shares	Q3 2016 Held for 9y 2m
5 Revolution Medicines, Inc. RVMD	Biotechnology Healthcare	$62.4M	3.66%	+$201.3K Bought	0.71% 1.3M shares	Q1 2023 Held for 2y 8m
6 Merus N.V. MRUS	Biotechnology Healthcare	$56.2M	3.30%	-$43.9M Sold	0.79% 597.1K shares	Q2 2023 Held for 2y 5m
7 Mirum Pharmaceuticals, Inc. MIRM	Biotechnology Healthcare	$55.8M	3.27%	-$4.2M Sold	1.52% 761.1K shares	Q3 2019 Held for 6y 2m
8 Insmed INSM	Biotechnology Healthcare	$55.4M	3.25%	-$20.2M Sold	0.18% 385.0K shares	Q2 2024 Held for 1y 5m
9 Travere Therapeutics, Inc. TVTX	Biotechnology Healthcare	$51.7M	3.04%	+$6.1M Bought	2.43% 2.2M shares	Q1 2015 Held for 10y 8m
10 ASND Ascendis Pharma ASND	Unknown Unknown	$42.6M	2.50%	-$497.0K Sold	— 214.5K shares	Q4 2022 Held for 2y 11m

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GthenH

Changes

Portfolio activity, position movements, and quarter-over-quarter changes in Rock Springs Capital Management LP's latest filing

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GthenC

Market Value

$1.7B

Prior: $1.6B

Q/Q Change

+6.5%

+$104.1M

Net Flows % of MV

-11.73%

Turnover Ratio

9.96%

New Purchases

6 stocks

$23.4M

Added To

24 stocks

+$47.5M

Sold Out Of

9 stocks

$70.5M

Reduced Holdings

36 stocks

-$200.3M

Increased Positions

Position	Shares Δ	Change
1 HTFL Heartflow, Inc. Common Stock HTFL	New	0 → 250.0K +$8.4M
2 MBX Biosciences, Inc. MBX	New	0 → 282.6K +$4.9M
3 BridgeBio Pharma BBIO	New	0 → 85.0K +$4.4M
4 Ocular Therapeutix OCUL	New	0 → 300.0K +$3.5M
5 CNTA Centessa Pharmaceuticals CNTA	New	0 → 69.2K +$1.7M

Decreased Positions

Position	Shares Δ	Change
1 Blueprint Medicines BPMC	Sold	185.5K → 0 −$23.8M
2 UnitedHealth Group UNH	Sold	50.5K → 0 −$15.8M
3 Oscar Health OSCR	Sold	700.0K → 0 −$15.0M
4 Nuvalent, Inc. NUVL	Sold	93.3K → 0 −$7.1M
5 Cullinan Therapeutics, Inc. CGEM	Sold	668.2K → 0 −$5.0M