Latest Period
Q1 2026
Security Snapshot
CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value per share (CSTL) Institutional Ownership
CUSIP: 14843C105
13F Institutional Holders and Ownership History from Q3 2019 to Q1 2026
Institutions Reporting
185
Shares (Excl. Options)
27,584,532
Price
$24.55
Save this security page for your next review
Keep this CUSIP in your watchlists so you can revisit quarter changes from one place. If you create an account from here, we will bring you back after verification.
- Security type / class
- Equity / Common Stock, $0.001 par value per share
- Symbol
- CSTL on Nasdaq
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 27,584,532
- Total 13F value
- $676,774,947
- Portfolio coverage rank
- 0%
- Share change
- +264,200
- Value change
- -$6,568,681
- Number of holders
- 185
- Shares outstanding
- 30,343,438
- SEC-reported price per share
- $24.81
- Insider filing price
- $24.81
Latest holder snapshot
5 signals
Issuer context
Names, identifiers, and filing context for this profile.
3 identity fields
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Key facts
- CSTL - CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value per share is tracked under CUSIP 14843C105.
- 185 institutions reported positions in Q1 2026.
- 5 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 196 to 185 between Q4 2025 and Q1 2026.
- SEC-reported value moved from $1,062,104,151 to $676,774,947.
Research use
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Evidence
Source: SEC Form 13F
Open SEC evidence
Latest holder context comes from 185 institutions filings for Q1 2026.
Security key
14843C105
Latest holder period
Q1 2026
13F holders
185
13D/G owners
5
CIK / CUSIP context first
Open Q1 2026 holders
CSTL full holder history
CASTLE BIOSCIENCES INC SEC filings
CASTLE BIOSCIENCES INC company facts
CASTLE BIOSCIENCES INC insider transactions
Broader feeds
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 14843C105:
13D/G owners
Significant owners
Large-stake holder rows connected to Schedule 13D/G evidence.
Rows
5
Security
CSTL
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| RTW INVESTMENTS, LP | 9.3% | +30% | $67,717,124 | +$15,788,056 | 2,758,335 | +30% | RTW Investments, LP | 31 Mar 2026 |
| BlackRock, Inc. | 8.2% | $47,017,281 | 2,338,005 | BlackRock, Inc. | 31 Mar 2025 | |||
| Portolan Capital Management, LLC | 4.4% | -20% | $33,149,448 | -$6,403,033 | 1,350,283 | -16% | Portolan Capital Management, LLC | 31 Mar 2026 |
| 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 Mar 2026, 185 institutional investors reported holding 27,584,532 shares of CASTLE BIOSCIENCES INC - Common Stock, $0.001 par value per share (CSTL). This represents 91% of the company’s total 30,343,438 outstanding shares.
13F concentration
Top 25 institutional shareholders
Largest 13F positions for this security by reported shares and value.
Top holder share
70%
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| BlackRock, Inc. | 9.8% | 2,982,946 | -3.9% | 0% | $73,231,325 |
| RTW INVESTMENTS, LP | 9.1% | 2,758,335 | +30% | 0.67% | $67,717,124 |
| PRINCIPAL FINANCIAL GROUP INC | 5.8% | 1,769,877 | -2.1% | 0.02% | $43,450,481 |
| Portolan Capital Management, LLC | 4.5% | 1,350,283 | -22% | 1.8% | $33,149,448 |
| VANGUARD CAPITAL MANAGEMENT LLC | 3.9% | 1,177,522 | 0% | 0% | $28,908,165 |
| DIMENSIONAL FUND ADVISORS LP | 3.4% | 1,039,761 | -9.1% | 0.01% | $25,523,454 |
| SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC | 3.1% | 940,685 | -11% | 1.1% | $23,093,817 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 2.8% | 861,771 | 0% | 0% | $21,156,478 |
| Allianz Asset Management GmbH | 2.7% | 811,324 | +30% | 0.02% | $19,918,004 |
| STATE STREET CORP | 2.5% | 769,079 | +4.4% | 0% | $18,880,889 |
| GEODE CAPITAL MANAGEMENT, LLC | 2.4% | 728,100 | +1.8% | 0% | $17,878,555 |
| AIGH Capital Management LLC | 1.9% | 590,601 | -5.5% | 3% | $14,499,255 |
| Qube Research & Technologies Ltd | 1.8% | 559,583 | +138% | 0.02% | $13,737,763 |
| PALISADE CAPITAL MANAGEMENT, LP | 1.8% | 535,884 | -5.6% | 0.44% | $13,155,952 |
| RENAISSANCE TECHNOLOGIES LLC | 1.8% | 532,800 | +8.1% | 0.02% | $13,080,240 |
| Nuveen, LLC | 1.7% | 522,127 | -0.49% | 0% | $12,818,217 |
| ACADIAN ASSET MANAGEMENT LLC | 1.6% | 484,441 | +24% | 0.02% | $11,884,000 |
| WASATCH ADVISORS LP | 1.5% | 455,036 | -15% | 0.07% | $11,171,134 |
| MORGAN STANLEY | 1.4% | 428,934 | +111% | 0% | $10,530,333 |
| EVENTIDE ASSET MANAGEMENT, LLC | 1.3% | 386,425 | +27% | 0.16% | $9,486,734 |
| Connor, Clark & Lunn Investment Management Ltd. | 1.2% | 377,082 | -2.9% | 0.02% | $9,257,363 |
| MILLENNIUM MANAGEMENT LLC | 1.2% | 353,319 | +14% | 0.01% | $8,673,981 |
| GOLDMAN SACHS GROUP INC | 1.1% | 341,171 | +19% | 0% | $8,375,748 |
| SCHRODER INVESTMENT MANAGEMENT GROUP | 0.99% | 298,941 | -39% | 0.01% | $7,040,061 |
| NORTHERN TRUST CORP | 0.9% | 273,101 | +4.1% | 0% | $6,704,630 |
Quarter history
Institutional holders across reporting periods
Holder count, reported shares/value, and median price by quarter.
Periods
27
Latest
Q1 2026
Rows shown
1-25 of 27
| Period | 13F Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 27,584,532 | $676,774,947 | -$6,568,681 | $24.55 | 185 |
| 2025 Q4 | 27,312,273 | $1,062,104,151 | +$35,010,645 | $38.90 | 196 |
| 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 |