Ranked by reported Q2 2026 13F market value
Share of total reported institutional value in CSTL held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | 3.3M | $78.5M | +10.4% | 10.854% | 0.00% |
| 2 | RTW INVESTMENTS, LP | 2.8M | $66.3M | +0.7% | 9.160% | 0.57% |
| 3 | PRINCIPAL FINANCIAL GROUP INC | 1.7M | $41.2M | -2.4% | 5.693% | 0.02% |
| 4 | VANGUARD CAPITAL MANAGEMENT LLC | 1.2M | $29.3M | +4.2% | 4.044% | 0.00% |
| 5 | Allianz Asset Management GmbH | 879K | $21.0M | +8.4% | 2.899% | 0.01% |
| 6 | VANGUARD PORTFOLIO MANAGEMENT LLC | 841K | $20.1M | -2.4% | 2.772% | 0.00% |
| 7 | SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC | 825K | $19.7M | -12.3% | 2.720% | 0.35% |
| 8 | STATE STREET CORP | 822K | $19.6M | +6.9% | 2.711% | 0.00% |
| 9 | GEODE CAPITAL MANAGEMENT, LLC | 796K | $19.0M | +9.3% | 2.624% | 0.00% |
| 10 | MACKENZIE FINANCIAL CORP | 794K | $18.9M | +970.7% | 2.616% | 0.02% |
| 11 | DIMENSIONAL FUND ADVISORS LP | 791K | $18.9M | -23.9% | 2.608% | 0.00% |
| 12 | Jefferies Financial Group Inc. | 647K | $15.4M | — | 2.135% | 0.10% |
| 13 | Qube Research & Technologies Ltd | 589K | $14.1M | +5.3% | 1.943% | 0.01% |
| 14 | AIGH Capital Management LLC | 545K | $13.0M | -7.7% | 1.797% | 0.82% |
| 15 | RENAISSANCE TECHNOLOGIES LLC | 371K | $8.9M | -30.3% | 1.224% | 0.01% |
| 16 | GOLDMAN SACHS GROUP INC | 358K | $8.5M | +5.1% | 1.182% | 0.00% |
| 17 | Point72 Asset Management, L.P. | 357K | $8.5M | — | 1.178% | 0.01% |
| 18 | KENNEDY CAPITAL MANAGEMENT LLC | 348K | $8.3M | — | 1.149% | 0.15% |
| 19 | Connor, Clark & Lunn Investment Management Ltd. | 332K | $7.9M | -12.0% | 1.094% | 0.01% |
| 20 | MORGAN STANLEY | 330K | $7.9M | -23.1% | 1.087% | 0.00% |
| 21 | Portolan Capital Management, LLC | 329K | $7.8M | -75.6% | 1.084% | 0.29% |
| 22 | PANAGORA ASSET MANAGEMENT INC | 301K | $7.2M | +35.4% | 0.993% | 0.02% |
| 23 | Allspring Global Investments Holdings, LLC | 292K | $7.0M | +82.0% | 0.964% | 0.01% |
| 24 | NORTHERN TRUST CORP | 285K | $6.8M | +4.4% | 0.940% | 0.00% |
| 25 | WASATCH ADVISORS LP | 279K | $6.7M | -38.6% | 0.921% | 0.04% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in CSTL — a direct measure of their conviction.
Filings activity in CSTL during Q2 2026, grouped by how each filer changed its position.
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q2 2026 | 175 | 6.4% | 90.30% | 1.63 pp | $625M | 4.9% |
| Q1 2026 | 187 | 3.1% | 91.93% | 0.78 pp | $658M | 37% |
| Q4 2025 | 193 | +14% | 92.71% | +1.04 pp | $1.04B | +77% |
| Q3 2025 | 170 | +11% | 91.67% | 0.43 pp | $590M | +14% |
| Q2 2025 | 153 | 15% | 92.10% | +3.16 pp | $518M | +7.3% |
| Q1 2025 | 179 | 6.8% | 88.94% | +1.43 pp | $483M | 23% |
| Q4 2024 | 192 | +6.1% | 87.51% | 2.43 pp | $631M | 6.6% |
| Q3 2024 | 181 | — | 89.94% | — | $676M | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying CSTL stock.
Based on Q2 2026 13F filings, institutional ownership of Castle Biosciences, Inc. stands at 90.3%, held across 175 reporting institutions.
BlackRock, Inc. is the largest reported institutional holder of CSTL, with approximately 3,291,963 shares worth $0.08B as of Q2 2026.
Yes — 2 widely-followed marquee investors appear among the top 25 institutional holders of CSTL, including RENAISSANCE TECHNOLOGIES LLC, Point72 Asset Management, L.P..
Our composite Smart Money Score for CSTL is 37 out of 100 (Bearish). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
18 institutions opened new positions in CSTL during Q2 2026, while 30 fully exited. 69 added to existing positions and 82 trimmed.
CSTL institutional ownership fell by 1.63 percentage points quarter-over-quarter, with a net change of -12 holders.
The top 10 institutions account for 53.3% of all reported 13F value in CSTL, and the top 25 account for 76.8%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Castle Biosciences, Inc. (CSTL) Institutional Ownership