13F Insight
DOSSIER · 13F-HR · Q1 2026

Rock Springs Capital Management LP

$1.7B in tracked AUM across 100 positions as of Q1 2026.

RS
CIK 0001595725 · last filed Mar 31, 2026
Total AUM
$1.7B
as of Q1 2026
Holdings
100
—
positions
Whale Score
63
63
tracked
Activity
—
no data
changes this Q
AI Analysis · Q1 2026

Portfolio Overview

Rock Springs Capital Management LP reported a significant contraction in portfolio value for the quarter ending September 30, 2025. The total assets under management (AUM) decreased by 31.9%, dropping from $1.60 billion to $1.09 billion. This reduction is attributed not only to potential market depreciation but also to substantial capital reallocation, evidenced by the high volume of portfolio turnover. The firm currently holds 62 positions, maintaining a concentrated str...

Key Holdings

The portfolio is heavily weighted toward healthcare, with argenx SE (ARGX) remaining the dominant position despite a reduction in stake. ARGX represents 9.64% of the portfolio ($105.29M), though the firm reduced its exposure by 18.8% ($8.41M). The second and third largest positions, Rhythm Pharmaceuticals (RYTM) at 6.63% and Revolution Medicines (RVMD) at 5.71%, highlight the firm's focus on biotechnology sub-sectors such as rare diseases and oncology. Notably, while Rhythm saw a significant reduction of 16.7% ($18.00M), Revolution Medicines saw a minor increase of 0.3%.

Quarter at a glance — Q1 2026

Position-change comparison pending.

No quarter-over-quarter changes available.

Top 10 holdings

By portfolio weight as of Q1 2026.

#HoldingValueSharesWeight
01
RVMD
REVOLUTION MEDICINES INC
$118M1.2M6.9%02
LLY
ELI LILLY & CO
$91M99K5.4%03
MDGL
MADRIGAL PHARMACEUTICALS INC
$90M171K5.3%04
MIRM
MIRUM PHARMACEUTICALS INC
$75M811K4.4%05
ARGX
ARGENX SE
$72M99K4.2%06
RYTM
RHYTHM PHARMACEUTICALS INC
$60M690K3.5%07
INSM
INSMED INC
$51M314K3.0%08
ASND
ASCENDIS PHARMA A/S
$44M194K2.6%09
XENE
XENON PHARMACEUTICALS INC
$44M763K2.6%10
TVTX
TRAVERE THERAPEUTICS INC
$44M1.5M2.6%

Filing history

2026Q1Mar 31
$1.7B▼ 13.0%
100 positionsView →2025Q4Dec 31
$2.0B▲ 78.5%
99 positionsView →2025Q3Sep 30
$1.1B▼ 31.9%
62 positionsView →2025Q2Jun 30
$1.6B▼ 8.2%
93 positionsLocked2025Q1Mar 31
$1.7B▼ 33.5%
96 positionsLocked2024Q4Dec 31
$2.6B▼ 14.5%
107 positionsLocked2024Q3Sep 30
$3.1B▼ 7.5%
109 positionsLocked2024Q2Jun 30
$3.3B▼ 15.7%
112 positionsLocked2024Q1Mar 31
$3.9B▼ 3.0%
114 positionsLocked2023Q4Dec 31
$4.1B▲ 8.8%
104 positionsLocked2023Q3Sep 30
$3.7B▼ 11.2%
120 positionsLocked2023Q2Jun 30
$4.2B▲ 0.3%
123 positionsLocked
Showing 12 of 48