CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value (CSTL) Institutional Ownership

13F Institutional Holders and Ownership History from Q3 2019 to Q4 2025

Type / Class
Equity / Common Stock, $0.001 par value
Symbol
CSTL on Nasdaq
Shares outstanding
29,378,292
Price per share
$39.16
All holders as of 31 Dec 2025
Q4 2025
Total 13F shares
27,290,205
Total reported value
$1,061,243,367
% of total 13F portfolios
0%
Share change
+817,673
Value change
+$35,479,717
Number of holders
193
Price from insider filings
$39.16
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors

Significant Owners of CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value (CSTL) based on Schedule 13D/G filings

Filer Ownership Change % Holdings Value Net Change Nb Shares Change % Reporting Name Report Period
BlackRock, Inc. 8.2% $47,017,281 2,338,005 BlackRock, Inc. 31 Mar 2025
RTW INVESTMENTS, LP 7.2% $84,757,547 2,115,237 RTW Investments, LP 31 Dec 2025
VANGUARD GROUP INC 6.5% $36,852,279 1,832,535 The Vanguard Group 31 Dec 2024
Portolan Capital Management, LLC 5.6% $32,399,201 1,611,099 Portolan Capital Management, LLC 07 Apr 2025
DIMENSIONAL FUND ADVISORS LP 3.9% -24% $44,494,010 -$12,848,347 1,143,799 -22% Dimensional Fund Advisors LP 31 Dec 2025
WASATCH ADVISORS LP 3.5% $20,078,930 998,455 WASATCH ADVISORS LP 31 Mar 2025

As of 31 Dec 2025, 193 institutional investors reported holding 27,290,205 shares of CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value (CSTL). This represents 93% of the company’s total 29,378,292 outstanding shares.

Top 25 Institutional Shareholders

The largest institutional shareholders of CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value (CSTL) together control 73% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.

Institution Ownership % Shares Held Share Change % Portfolio % Holdings Value
BlackRock, Inc. 11% 3,105,246 -2.7% 0% $120,794,069
VANGUARD GROUP INC 7.5% 2,199,829 +1.3% 0% $85,573,349
RTW INVESTMENTS, LP 7.2% 2,115,237 0.82% $82,282,719
PRINCIPAL FINANCIAL GROUP INC 6.2% 1,807,644 +0.74% 0.04% $70,317,352
Portolan Capital Management, LLC 5.9% 1,729,463 +14% 3.6% $67,276,111
DIMENSIONAL FUND ADVISORS LP 3.9% 1,143,799 -22% 0.01% $44,494,673
SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC 3.6% 1,058,725 +165% 1.2% $41,184,403
STATE STREET CORP 2.5% 736,454 +1.7% 0% $28,648,061
GEODE CAPITAL MANAGEMENT, LLC 2.4% 714,913 +2.3% 0% $27,814,871
AIGH Capital Management LLC 2.1% 624,719 -12% 7.2% $24,301,569
Allianz Asset Management GmbH 2.1% 622,299 -4% 0.03% $24,207,431
PALISADE CAPITAL MANAGEMENT, LP 1.9% 567,777 -11% 0.65% $22,086,525
WASATCH ADVISORS LP 1.8% 537,241 -20% 0.12% $20,898,675
Nuveen, LLC 1.8% 524,681 -45% 0.01% $20,410,091
RENAISSANCE TECHNOLOGIES LLC 1.7% 493,100 -12% 0.03% $19,181,590
SCHRODER INVESTMENT MANAGEMENT GROUP 1.7% 492,161 -0.56% 0.01% $19,346,849
ACADIAN ASSET MANAGEMENT LLC 1.3% 390,406 -14% 0.02% $15,180,000
Connor, Clark & Lunn Investment Management Ltd. 1.3% 388,491 +16% 0.04% $15,112,300
CITADEL ADVISORS LLC 1.2% 366,356 +46% 0.01% $14,251,249
MILLENNIUM MANAGEMENT LLC 1.1% 308,914 -46% 0.01% $12,016,755
EVENTIDE ASSET MANAGEMENT, LLC 1% 305,000 0.19% $11,864,500
GOLDMAN SACHS GROUP INC 0.98% 287,235 -17% 0% $11,173,441
KORNITZER CAPITAL MANAGEMENT INC /KS 0.91% 267,733 -3.8% 0.22% $10,414,814
BANK OF AMERICA CORP /DE/ 0.9% 263,019 -17% 0% $10,231,439
NORTHERN TRUST CORP 0.89% 262,243 -7.1% 0% $10,201,253

Institutional Holders of CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value (CSTL) across Reporting Periods

Period Reported Shares, Excl. Options Value, Excl. Options Value Change Price (Median) Investors
2025 Q4 27,290,205 $1,061,243,367 +$35,479,717 $38.90 193
2025 Q3 26,525,698 $603,808,247 +$704,267 $22.77 170
2025 Q2 26,536,136 $541,803,165 +$16,367,707 $20.42 151
2025 Q1 25,785,418 $516,159,447 -$22,608,207 $20.02 180
2024 Q4 26,505,010 $706,396,254 +$8,987,296 $26.65 197
2024 Q3 25,823,597 $736,872,924 +$15,687,154 $28.52 185
2024 Q2 25,237,547 $549,387,569 +$5,246,303 $21.77 158
2024 Q1 24,977,542 $553,239,171 +$24,692,740 $22.15 148
2023 Q4 23,883,435 $515,429,989 +$17,867,692 $21.58 150
2023 Q3 23,151,664 $391,032,725 +$7,780,165 $16.89 133
2023 Q2 22,797,205 $312,778,898 -$3,698,099 $13.72 128
2023 Q1 22,094,408 $501,938,865 +$5,568,015 $22.72 148
2022 Q4 22,279,170 $524,435,055 +$5,715,957 $23.54 152
2022 Q3 21,906,465 $571,186,085 -$14,799,148 $26.08 152
2022 Q2 22,558,449 $495,033,707 -$115,268,932 $21.95 141
2022 Q1 22,780,568 $1,019,269,661 +$62,738,499 $44.86 153
2021 Q4 21,449,510 $918,308,511 -$59,908,643 $42.87 153
2021 Q3 20,974,973 $1,396,164,362 +$40,585,506 $66.50 182
2021 Q2 20,801,213 $1,521,315,172 -$4,483,937 $73.33 176
2021 Q1 21,328,263 $1,459,495,488 +$90,506,347 $68.46 173
2020 Q4 19,063,994 $1,280,953,552 +$376,683,100 $67.15 160
2020 Q3 13,395,783 $689,395,356 +$88,062,594 $51.45 144
2020 Q2 11,747,525 $443,283,646 +$169,050,988 $37.69 125
2020 Q1 7,359,714 $219,391,385 +$66,312,670 $29.81 88
2019 Q4 5,108,808 $175,588,000 +$15,879,309 $34.37 66
2019 Q3 4,868,946 $88,077,000 +$69,427,000 $18.09 56