Castle Biosciences CSTL Institutional Ownership

NASDAQ CSTL

$34.37 +1.22 (+3.68%)

At close: Oct 21, 2026 · 4:00 PM EDT

Institutions by Trading Activity

177 Institutions

Increased 104 58.8%

Unchanged 18 10.2%

Reduced 55 31.1%

Ownership Statistics

13F · as of 30 Jun, 2026

Institutional Ownership

89.58%

▼-1.55 pp QoQ

Shares Held by Institutions

27.33Mn

of 30.51Mn outstanding

▼-1.01% QoQ

Shares Outstanding

30.51Mn

3.18Mn held outside 13F filers

Institutional Investors

177

filed 13F for Jun 2026

▼-8 vs prior quarter

Net Shares Added (QoQ)

-278.36K

distributed since last quarter

Value of Holdings

$906.02Mn

reported market value

Shares Owned by Institutions

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Shares Purchased/Sold by Institutions

Accumulated Distributed

Latest quarter —

Net over range —

Accumulating quarters —

Ownership Summary

Updated Oct 11, 2026

Castle Biosciences Inc (NASDAQ:CSTL) counted 177 institutional investors among its 13F-reported shareholders for the quarter ended June 30, 2026.

Collectively, these holders controlled 89.58% of Castle Biosciences' outstanding shares in Q2 2026, down from 91.13% in Q1 2026.
Total shares held in Castle Biosciences fell 1.01% from Q1 2026, while the number of holders rose 20.41% from Q2 2025.
Among the 177 holders of Castle Biosciences, 104 added to their positions, 55 reduced their stakes and 18 left their positions unchanged.
The aggregate institutional position in Castle Biosciences was 27.33Mn shares at the end of Q2 2026, down 278.36K from the prior quarter and up 1.88Mn from a year earlier.
As of June 30, 2026, the biggest holder of Castle Biosciences was BlackRock, Inc. with 3.29Mn shares, or 10.79% of shares outstanding.
Among existing holders, the largest additions to Castle Biosciences in Q2 2026 came from Mackenzie Financial Corp (+719.4K shares), Acadian Asset Management LLC (+434.23K shares), BlackRock, Inc. (+309.02K shares), Citadel Advisors LLC (+144.38K shares) and Allspring Global Investments Holdings, LLC (+131.81K shares).
On the other side, among holders that kept a position in Castle Biosciences, the largest reductions in Q2 2026 came from Portolan Capital Management, LLC (-1.02Mn shares), Palisade Capital Management, LP (-303.95K shares), Nuveen, LLC (-290.4K shares), Dimensional Fund Advisors LP (-248.68K shares) and Tudor Investment Corp (-208.52K shares).
Per Business Quant data, the 10 largest holders of Castle Biosciences at the end of Q2 2026 were BlackRock, Inc. (3.29Mn shares), RTW Investments, LP (2.78Mn shares), Principal Financial Group Inc (1.73Mn shares), Vanguard Capital Management LLC (1.23Mn shares), Acadian Asset Management LLC (918.67K shares), Vanguard Portfolio Management LLC (840.78K shares), Summit Partners Public Asset Management, LLC (824.87K shares), State Street Corp (822.08K shares), Allianz Asset Management GmbH (811.32K shares) and Geode Capital Management, LLC (795.91K shares).

Form 13F Holdings

178 Institutional Holders

Report period 30 Jun, 2026

Total shares held 27.33Mn

Of outstanding 89.58%

#	Institution	CIK	Shares Held	% of Outstanding	Change (QoQ)	Change (%)	Value (USD)
1	BlackRock, Inc.	0002012383	3,291,963	10.79%	▲309,017	+10.36%	$78.51Mn
2	RTW INVESTMENTS, LP	0001493215	2,778,335	9.11%	▲20,000	+0.73%	$66.26Mn
3	Principal Financial Group Inc	0001126328	1,726,648	5.66%	▼43,229	-2.44%	$41.18Mn
4	VANGUARD CAPITAL MANAGEMENT LLC	0002100119	1,226,497	4.02%	▲48,975	+4.16%	$29.25Mn
5	ACADIAN ASSET MANAGEMENT LLC	0000916542	918,668	3.01%	▲434,227	+89.63%	$21.90K
6	VANGUARD PORTFOLIO MANAGEMENT LLC	0002100121	840,785	2.76%	▼20,986	-2.44%	$20.05Mn
7	SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC	0001638555	824,872	2.70%	▼115,813	-12.31%	$19.67Mn
8	State Street Corp	0000093751	822,079	2.69%	▲53,000	+6.89%	$19.63Mn
9	Allianz Asset Management GmbH	0001535323	811,324	2.66%	0	0.00%	$19.92Mn
10	GEODE CAPITAL MANAGEMENT, LLC	0001214717	795,912	2.61%	▲67,812	+9.31%	$18.99Mn
11	MACKENZIE FINANCIAL CORP	0000919859	793,507	2.60%	▲719,396	+970.70%	$18.93Mn
12	DIMENSIONAL FUND ADVISORS LP	0000354204	791,085	2.59%	▼248,676	-23.92%	$18.87Mn
13	Jefferies Financial Group Inc.	0000096223	647,391	2.12%	▲647,391	0.00%	$15.44Mn
14	Qube Research & Technologies Ltd	0001729829	589,300	1.93%	▲29,717	+5.31%	$14.05Mn
15	AIGH Capital Management LLC	0001835943	545,101	1.79%	▼45,500	-7.70%	$13.00Mn
16	RENAISSANCE TECHNOLOGIES LLC	0001037389	371,200	1.22%	▼161,600	-30.33%	$8.85Mn
17	Goldman Sachs Group Inc	0000886982	358,397	1.17%	▲17,226	+5.05%	$8.55Mn
18	Point72 Asset Management, L.P.	0001603466	357,317	1.17%	▲357,317	0.00%	$8.52Mn
19	KENNEDY CAPITAL MANAGEMENT LLC	0000884589	348,371	1.14%	▲348,371	0.00%	$8.31Mn
20	Connor, Clark & Lunn Investment Management Ltd.	0001596800	331,727	1.09%	▼45,355	-12.03%	$7.91Mn

Showing 1 to 20 of 178 holders