CASTLE BIOSCIENCES INC (CSTL) Institutional Ownership Changes & 13F Activity

CASTLE BIOSCIENCES INC (CSTL) institutional ownership data tracks hedge funds, asset managers, and other institutional investors based on recent SEC 13F filings (Q1 2026). This page analyzes institutional buying and selling activity, new holdings, and sold-out positions among tracked filers. Notable filers include Renaissance Technologies LLC and ARK Invest.

Portfolio quarterNameTypeQuantityRemainingReported stock balance
Q1 2026Renaissance Technologies LLCBuy39,700532,800$13,080,240
Q4 2025Renaissance Technologies LLCSell-69,500493,100$19,181,590
Q3 2025Renaissance Technologies LLCSell-107,900562,600$12,810,402
Q2 2025Renaissance Technologies LLCSell-30,700670,500$13,691,610
Q1 2025Renaissance Technologies LLCBuy16,200701,200$14,038,024
Q4 2024Renaissance Technologies LLCBuy195,438685,000$18,255,250
Q3 2024Renaissance Technologies LLCBuy188,062489,562$13,962,308
Q2 2024Renaissance Technologies LLCBuy96,800301,500$6,563,655
Q1 2024Renaissance Technologies LLCBuy92,300204,700$4,534
Q4 2023Renaissance Technologies LLCBuy5,600112,400$2,426
Q3 2023Renaissance Technologies LLCSell-65,600106,800$1,804
Q2 2023Renaissance Technologies LLCBuy136,000172,400$2,365
Q1 2023Renaissance Technologies LLCBuy14,30036,400$827
Q4 2022Renaissance Technologies LLCBuy5,10022,100$520
Q3 2022Renaissance Technologies LLCSell-40017,000$443
Q2 2022ARK InvestSell-1,170,1110$0
Q2 2022Renaissance Technologies LLCSell-7,60017,400$382
Q1 2022Renaissance Technologies LLCSell-109,28125,000$1,122
Q1 2022ARK InvestSell-43,0961,170,111$52,491
Q4 2021ARK InvestSell-844,6601,213,207$52,010
Q4 2021Renaissance Technologies LLCBuy106,781134,281$5,757
Q3 2021ARK InvestSell-467,7462,057,867$136,848
Q2 2021ARK InvestSell-71,6752,525,613$185,203
Q1 2021ARK InvestBuy528,6962,597,288$177,810
Q1 2021Renaissance Technologies LLCBuy23,60027,500$1,883
Q4 2020ARK InvestBuy1,620,8672,068,592$138,906
Q3 2020Renaissance Technologies LLCSell-38,9363,900$201
Q3 2020ARK InvestSell-26,045447,725$23,035
Q2 2020ARK InvestBuy253,318473,770$17,856
Q2 2020Renaissance Technologies LLCBuy9,63642,836$1,614

Frequently asked questions about CSTL activity

  • Which institutional owners are buying CSTL?

    Institutional owners buying CSTL include investors who have either initiated new positions or increased their existing holdings based on recent SEC 13F filings. The activity table above highlights which funds added shares in the latest reporting periods and how their positions changed over time.

  • What does "buy" mean in CSTL activity?

    "Buy" means an investor increased their reported position in CSTL compared to the prior reporting period. This reflects growing exposure to CASTLE BIOSCIENCES INC (CSTL) rather than necessarily a brand-new position (though new positions also appear as buys when prior quantity was zero).

  • Is institutional interest in CSTL increasing?

    Institutional interest in CSTL can be assessed by comparing the number of tracked funds adding or increasing positions versus those trimming or exiting across the periods shown. A higher number of additions typically signals increasing participation among large filers, but it should be read alongside position sizes and the full table.

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