CASTLE BIOSCIENCES INC (CSTL) Top Institutional Shareholders
CASTLE BIOSCIENCES INC (CSTL) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended March 31, 2026. The institutional investors covered on this page collectively reported approximately $652.87M in CSTL holdings during the latest filing period.
Blackrock, Inc. is currently the largest disclosed institutional shareholder of CSTL tracked by InsiderSet, reporting ownership valued at approximately $73.23M in its March 31, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $60.40M, representing an estimated loss of -17.52% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 54% of the total disclosed CSTL value among the investors covered in this analysis. Major shareholders include Blackrock, Inc., Rtw Investments, Lp, Principal Financial Group Inc, and several other long-term asset managers with concentrated positions in CASTLE BIOSCIENCES INC (CSTL).
This page ranks the largest institutional CSTL shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
183
Total Reported Value
$652.87M
Largest Holder
Blackrock, Inc.
Largest Position
$73.23M
Insider Transactions (90d)
0
Latest Filing Quarter
Q1 2026
New Institutional Positions
170
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Blackrock, Inc. | 0.00% | 2,982,946 | $73,231,325 | $60,404,657 | -$12,826,669 | -17.52% | |
| Rtw Investments, Lp | 0.67% | 2,758,335 | $67,717,124 | $55,856,284 | -$11,860,840 | -17.52% | |
| Principal Financial Group Inc | 0.02% | 1,769,877 | $43,450,481 | $35,840,009 | -$7,610,472 | -17.52% | |
| Portolan Capital Management, Llc | 1.76% | 1,350,283 | $33,149,448 | $27,343,231 | -$5,806,217 | -17.52% | |
| Vanguard Capital Management Llc | 0.00% | 1,177,522 | $28,908,165 | $23,844,821 | -$5,063,345 | -17.52% | |
| Dimensional Fund Advisors Lp | 0.01% | 1,039,761 | $25,523,454 | $21,055,160 | -$4,468,294 | -17.51% | |
| Summit Partners Public Asset Management, Llc | 1.09% | 940,685 | $23,093,817 | $19,048,871 | -$4,044,946 | -17.52% | |
| Vanguard Portfolio Management Llc | 0.00% | 861,771 | $21,156,478 | $17,450,863 | -$3,705,615 | -17.52% | |
| Allianz Asset Management Gmbh | 0.02% | 811,324 | $19,918,004 | $16,429,311 | -$3,488,693 | -17.52% | |
| State Street Corp | 0.00% | 769,079 | $18,880,889 | $15,573,850 | -$3,307,039 | -17.52% | |
| Geode Capital Management, Llc | 0.00% | 728,100 | $17,878,555 | $14,744,025 | -$3,134,530 | -17.53% | |
| Aigh Capital Management Llc | 2.97% | 590,601 | $14,499,255 | $11,959,670 | -$2,539,585 | -17.52% | |
| Qube Research & Technologies Ltd | 0.02% | 559,583 | $13,737,763 | $11,331,556 | -$2,406,207 | -17.52% | |
| Palisade Capital Management, Lp | 0.44% | 535,884 | $13,155,952 | $10,851,651 | -$2,304,301 | -17.52% | |
| Renaissance Technologies LLC | Jim Simons | 0.02% | 532,800 | $13,080,240 | $10,789,200 | -$2,291,040 | -17.52% |
| Nuveen, Llc | 0.00% | 522,127 | $12,818,217 | $10,573,072 | -$2,245,145 | -17.52% | |
| Wasatch Advisors Lp | 0.07% | 455,036 | $11,171,134 | $9,214,479 | -$1,956,655 | -17.52% | |
| Morgan Stanley | 0.00% | 428,934 | $10,530,333 | $8,685,914 | -$1,844,420 | -17.52% | |
| Eventide Asset Management, Llc | 0.16% | 386,425 | $9,486,734 | $7,825,106 | -$1,661,628 | -17.52% | |
| Connor, Clark & Lunn Investment Management Ltd. | 0.02% | 377,082 | $9,257,363 | $7,635,911 | -$1,621,453 | -17.52% | |
| Millennium Management Llc | 0.01% | 353,319 | $8,673,981 | $7,154,710 | -$1,519,271 | -17.52% | |
| Goldman Sachs Group Inc | 0.00% | 341,171 | $8,375,748 | $6,908,713 | -$1,467,035 | -17.52% | |
| Schroder Investment Management Group | 0.01% | 298,941 | $7,040,061 | $6,053,555 | -$986,506 | -14.01% | |
| Northern Trust Corp | 0.00% | 273,101 | $6,704,630 | $5,530,295 | -$1,174,335 | -17.52% | |
| Silvercrest Asset Management Group Llc | 0.05% | 268,535 | $6,592,534 | $5,437,834 | -$1,154,700 | -17.52% | |
| Kornitzer Capital Management Inc | 0.14% | 264,396 | $6,490,922 | $5,354,019 | -$1,136,903 | -17.52% | |
| Bridgeway Capital Management, Llc | 0.13% | 255,184 | $6,264,767 | $5,167,476 | -$1,097,291 | -17.52% | |
| Two Sigma Investments, Lp | 0.01% | 248,840 | $6,109,022 | $5,039,010 | -$1,070,012 | -17.52% | |
| Advisors Capital Management, Llc | 0.07% | 248,376 | $6,097,630 | $5,029,614 | -$1,068,016 | -17.52% | |
| Charles Schwab Investment Management Inc | 0.00% | 241,880 | $5,938,154 | $4,898,070 | -$1,040,084 | -17.52% | |
| New York State Common Retirement Fund | 0.01% | 233,046 | $5,721,279 | $4,719,182 | -$1,002,098 | -17.52% | |
| Tudor Investment Corp Et Al | 0.03% | 222,982 | $5,474,208 | $4,515,386 | -$958,823 | -17.52% | |
| Panagora Asset Management Inc | 0.02% | 222,353 | $5,458,766 | $4,502,648 | -$956,118 | -17.52% | |
| D. E. Shaw & Co., Inc. | 0.00% | 211,966 | $5,203,765 | $4,292,312 | -$911,454 | -17.52% | |
| Vanguard Fiduciary Trust Co | 0.00% | 188,211 | $4,620,580 | $3,811,273 | -$809,307 | -17.52% | |
| Allspring Global Investments Holdings, Llc | 0.01% | 160,663 | $3,944,277 | $3,253,426 | -$690,851 | -17.52% | |
| Campbell & Co Investment Adviser Llc | 0.21% | 148,824 | $3,653,629 | $3,013,686 | -$639,943 | -17.52% | |
| Empowered Funds, Llc | 0.02% | 132,184 | $3,245,117 | $2,676,726 | -$568,391 | -17.52% | |
| Trexquant Investment Lp | 0.02% | 130,434 | $3,202,155 | $2,641,289 | -$560,867 | -17.52% | |
| Parkman Healthcare Partners Llc | 0.32% | 126,150 | $3,096,983 | $2,554,538 | -$542,446 | -17.52% | |
| Bnp Paribas Financial Markets | 0.00% | 122,156 | $2,998,930 | $2,473,659 | -$525,271 | -17.52% | |
| Citadel Advisors Llc | 0.00% | 120,977 | $2,969,986 | $2,449,784 | -$520,202 | -17.52% | |
| Franklin Resources Inc | 0.00% | 90,909 | $2,231,816 | $1,840,907 | -$390,909 | -17.52% | |
| Bank Of New York Mellon Corp | 0.00% | 88,654 | $2,176,446 | $1,795,244 | -$381,203 | -17.51% | |
| American Century Companies Inc | 0.00% | 79,107 | $1,942,077 | $1,601,917 | -$340,160 | -17.52% | |
| Orion Porfolio Solutions, Llc | 0.02% | 74,896 | $1,838,697 | $1,516,644 | -$322,053 | -17.52% | |
| Mackenzie Financial Corp | 0.00% | 74,111 | $1,819,425 | $1,500,748 | -$318,677 | -17.52% | |
| Bank Of America Corp | 0.00% | 67,810 | $1,664,735 | $1,373,153 | -$291,583 | -17.52% | |
| Summittx Capital, L.P. | 0.05% | 67,033 | $1,645,660 | $1,357,418 | -$288,242 | -17.52% | |
| Ubs Am, A Distinct Business Unit Of Ubs Asset Management Americas Llc | 0.00% | 64,964 | $1,594,866 | $1,315,521 | -$279,345 | -17.52% |
Frequently asked questions about CSTL
Who owns the most CSTL stock?
The largest holders of CSTL are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for CASTLE BIOSCIENCES INC (CSTL).
Is CSTL widely held by superinvestors?
Many widely followed stocks like CSTL appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly CSTL is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.