RTW INVESTMENTS, LP

Position in CSTL — Castle Biosciences Inc

CIK 1493215 NEW YORK, NY

Position in CSTL

as of Mar 31, 2026 · filed May 15, 2026 Compact

Position Value

$67,717,124

-$14,565,595 QoQ

Shares Held

2,758,335

+30.4% QoQ

Ownership

9.09%

of shares outstanding

% of Portfolio

0.67%

of 13F equity value

Holder Rank

—

not a current holder

Holding Since

Mar 2020

15 quarters on record

Voting authority Sole 100% Shared 0% None 0%

Healthcare · as of Mar 31, 2026

RTW INVESTMENTS, LP holds $723,822,310 across 7 Diagnostics & Research names. CSTL ranks #4 (9.4% of the industry book) .

#	Ticker	Company	Shares	Value (USD)
1	NTRA	Natera, Inc.	1,250,000	$249,987,500
2	RDNT	RadNet, Inc.	4,285,000	$239,488,650
3	GH	Guardant Health, Inc.	1,481,033	$136,803,018
4	CSTL	Castle Biosciences Inc This page	2,758,335	$67,717,124
5	FLGT	Fulgent Genetics, Inc.	1,289,000	$20,495,100
6	FRNM	Freenome, Inc.	742,500	$8,145,225
7	XGN	Exagen Inc.	395,231	$1,185,693

15 filing rows on record

Report Date	Value (USD)	Shares	Change	Type	Discretion	Filed
2026-03-31	$67,717,124	2,758,335	+30.4%	Shares	Sole	2026-05-15
2025-12-31	$82,282,719	2,115,237	+718.3%	Shares	Sole	2026-02-17
2023-03-31	$5,873,074	258,498	-50.0%	Shares	Sole	2023-05-15
2022-12-31	$12,170,062	516,995	0.0%	Shares	Sole	2023-02-14
2022-09-30	$13,483,229	516,995	-43.4%	Shares	Sole	2022-11-14
2022-06-30	$20,057,668	913,789	+84.0%	Shares	Sole	2022-08-15
2022-03-31	$22,280,840	496,675	-17.1%	Shares	Sole	2022-05-16
2021-12-31	$25,679,515	599,009	0.0%	Shares	Sole	2022-02-14
2021-09-30	$39,834,098	599,009	-25.0%	Shares	Sole	2021-11-15
2021-06-30	$58,591,329	799,009	0.0%	Shares	Sole	2021-08-13
2021-03-31	$54,700,156	799,009	0.0%	Shares	Sole	2021-05-14
2020-12-31	$53,653,454	799,009	+7.4%	Shares	Sole	2021-02-16
2020-09-30	$38,260,380	743,642	-7.5%	Shares	Sole	2020-11-16
2020-06-30	$30,284,291	803,510	+15.1%	Shares	Sole	2020-08-14
2020-03-31	$20,810,897	698,118	—	Shares	Sole	2020-05-15
No filing history on record for this holder in this stock.