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Equibles

RTW INVESTMENTS, LP

Position in CSTL — Castle Biosciences Inc

CIK 1493215 NEW YORK, NY
Back to CSTL Full portfolio

Position in CSTL

as of Jun 30, 2026 · filed Aug 14, 2026
Position Value
$66,263,289
-$1,453,835 QoQ
Shares Held
2,778,335
+0.7% QoQ
Ownership
9.09%
of shares outstanding
% of Portfolio
0.57%
of 13F equity value
Holder Rank
#2
of 176 holders
Holding Since
Mar 2020
16 quarters on record
Voting authority Sole 100% Shared 0% None 0%

Common Shares in CSTL Over Time

Shares Held

Position Value (USD)

Position in Diagnostics & Research

Healthcare · as of Jun 30, 2026

RTW INVESTMENTS, LP holds $911,620,118 across 7 Diagnostics & Research names. CSTL ranks #4 (7.3% of the industry book) .

# Ticker Company Shares Value (USD) Open
1 RDNT
RadNet, Inc.
 4,846,958 $298,911,899
2 NTRA
Natera, Inc.
 1,000,000 $271,450,000
3 GH
Guardant Health, Inc.
 1,481,033 $222,199,380
4 CSTL
Castle Biosciences Inc
This page 		2,778,335 $66,263,289
5 DHR
Danaher Corp /De/
 230,000 $43,810,400
6 FRNM
Freenome, Inc.
 742,500 $8,078,400
7 XGN
Exagen Inc.
 195,000 $906,750

All Filings in CSTL

Export CSV
16 filing rows on record
Report Date Value (USD) Shares
2026-06-30 $66,263,289 2,778,335
2026-03-31 $67,717,124 2,758,335
2025-12-31 $82,282,719 2,115,237
2023-03-31 $5,873,074 258,498
2022-12-31 $12,170,062 516,995
2022-09-30 $13,483,229 516,995
2022-06-30 $20,057,668 913,789
2022-03-31 $22,280,840 496,675
2021-12-31 $25,679,515 599,009
2021-09-30 $39,834,098 599,009
2021-06-30 $58,591,329 799,009
2021-03-31 $54,700,156 799,009
2020-12-31 $53,653,454 799,009
2020-09-30 $38,260,380 743,642
2020-06-30 $30,284,291 803,510
2020-03-31 $20,810,897 698,118