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Castle Biosciences Ownership | Who Owns Castle Biosciences?

OverviewForecastRevenueFinancialsChartTranscripts

Castle Biosciences Ownership Summary

Castle Biosciences is owned by 94.10% institutional investors, 2.38% insiders, and 3.53% retail investors. Blackrock is the largest institutional shareholder, holding 11.08% of CSTL shares. Bellevue Healthcare Ord is the top mutual fund, with 4.32% of its assets in Castle Biosciences shares.

CSTL Ownership Benchmark

TypeName% Inst% Insiders% Retail
StockCastle Biosciences94.10%2.38%3.53%
SectorHealthcare Stocks 35.34%11.88%52.77%
IndustryDiagnostics & Research Stocks50.92%10.77%38.30%

Institutional Shareholders

Top Institutional Shareholders by Total Shares

HolderShares% HoldingValue
Blackrock3.04M11.08%$66.29M
Blackrock funding, inc. /de2.98M10.17%$73.23M
Rtw investments, lp2.76M9.40%$67.72M
Vanguard group2.20M8.78%$85.57M
Principal financial group1.77M6.03%$43.45M
Portolan capital management1.35M4.60%$33.15M
Dimensional fund advisors lp1.04M3.54%$25.52M
Summit partners public asset management940.68K3.21%$23.09M
Allianz asset management gmbh811.32K2.77%$19.92M
State street769.08K2.62%$18.88M

Top Institutional Shareholders by % of Total Assets

HolderShares% AssetsValue
Aigh capital management590.60K1.98%$14.50M
Portolan capital management1.35M1.76%$33.15M
Rtw investments, lp2.76M0.67%$67.72M
Summit partners public asset management940.68K0.62%$23.09M
Formula growth46.00K0.51%$1.13M
Palisade capital management, lp535.88K0.44%$13.16M
Perkins capital management15.41K0.35%$378.44K
Parkman healthcare partners126.15K0.32%$3.10M
Green alpha advisors9.95K0.24%$244.15K
Campbell & co investment adviser148.82K0.21%$3.65M

Top Buyers

HolderShares% AssetsChange
Rtw investments, lp2.76M0.67%643.10K
Blackrock3.04M0.00%449.29K
Qube research559.58K0.02%324.06K
Morgan stanley428.93K0.00%225.36K
Sg americas securities244.89K0.01%223.62K

Top Sellers

HolderShares% AssetsChange
Park west asset management---556.49K
Portolan capital management1.35M1.76%-379.18K
Bellevue group---301.10K
Soleus capital management---252.92K
Citadel advisors120.98K0.00%-245.38K

New Positions

HolderShares% AssetsChangeValue
Vanguard fiduciary trust188.21K0.00%188.21K$4.62M
Formula growth46.00K0.51%46.00K$1.13M
Kbc group nv36.93K0.00%36.93K$907.00K
Nomura35.75K0.00%35.75K$877.61K
Exoduspoint capital management, lp32.61K0.01%32.61K$800.53K

Sold Out

HolderChange
Nelson, van denburg & campbell wealth management group-1.00
National bank of canada /fi/-1.00
Stephens consulting-2.00
Colonial trust advisors-6.00
Skopos labs-11.00

Institutional Ownership Trends

DateHoldingsChange %SharesChange %OwnershipChange %Increased PositionChange %Decreased PositionChange %
Mar 31, 2026188-4.57%27,601,5221.07%940.79%101-3.81%59-16.90%
Dec 31, 2025157-10.80%19,552,468-26.63%780.92%80-18.37%575.56%
Sep 30, 202517112.50%26,525,363-0.04%911.09%939.41%5420.00%
Jun 30, 2025151-17.03%26,530,4542.55%911.12%85-19.81%44-18.52%
Mar 31, 2025178-13.17%25,557,223-3.26%890.99%105-2.78%53-19.70%

Top Mutual Funds Shareholders

HolderShares% HoldingChange
Bellevue Healthcare Ord1.20M4.32%1.20M
Vanguard US Total Market Shares ETF829.40K2.96%-
Vanguard Total Stock Mkt Idx Inv823.96K2.72%-
Principal U.S. Small Cap Select Equity753.64K2.49%-80.80K
Principal SmallCap R5753.64K2.49%-8.80K
Principal U.S. Small Cap Equity753.64K2.49%-80.80K
Strategic Advisers U.S. Total Stock{mg}693.06K2.47%-
Wasatch Small Cap Growth Investor675.19K2.41%-14.34K
Strategic Advisers Small-Mid Cap665.91K2.40%62.85K
iShares Russell 2000 ETF678.19K2.24%5.73K

Recent Insider Transactions

DateNameRoleActivityValue
May 07, 2026MAETZOLD DEREK J Pres. & Chief Exec. OfficerSell$21.75K
May 07, 2026MAETZOLD DEREK J Pres. & Chief Exec. OfficerSell$3.79K
May 07, 2026MAETZOLD DEREK J Pres. & Chief Exec. OfficerSell$25.59K
May 07, 2026MAETZOLD DEREK J Pres. & Chief Exec. OfficerSell$4.47K
May 07, 2026MAETZOLD DEREK J Pres. & Chief Exec. OfficerSell$117.20K

Insider Transactions Trends

DateBuySell
2026 Q2-8
2026 Q1-26
2025 Q4-26
2025 Q3-7
2025 Q2-20

CSTL Ownership FAQ

Who Owns Castle Biosciences?

Castle Biosciences shareholders are primarily institutional investors at 94.10%, followed by 2.38% insiders and 3.52% retail investors. The average institutional ownership in Castle Biosciences's industry, Diagnostics & Research Stocks, is 50.92%, which Castle Biosciences exceeds.

Who owns the most shares of Castle Biosciences?

Castle Biosciences’s largest shareholders are Blackrock (3.04M shares, 11.08%), Blackrock funding, inc. /de (2.98M shares, 10.17%), and Rtw investments, lp (2.76M shares, 9.40%). Together, they hold 30.65% of Castle Biosciences’s total shares outstanding.

Does Blackrock own Castle Biosciences?

Yes, BlackRock owns 11.08% of Castle Biosciences, totaling 3.04M shares as of Jun 2024. This represents 0.00% of BlackRock's total assets, with a market value of 66.29M$. In the last quarter, BlackRock increased its holdings by 449.29K shares, a 17.31% change.

Who is Castle Biosciences’s biggest shareholder by percentage of total assets invested?

Aigh capital management is Castle Biosciences’s biggest shareholder by percentage of total assets invested, with 1.98% of its assets in 590.6K Castle Biosciences shares, valued at 14.5M$.

Who is the top mutual fund holder of Castle Biosciences shares?

Bellevue Healthcare Ord is the top mutual fund holder of Castle Biosciences shares, with 4.32% of its total shares outstanding invested in 1.2M Castle Biosciences shares.

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