Castle Biosciences, Inc. (CSTL)
Nasdaq: CSTL · Services-Medical Laboratories · Friendswood, TX · filing with the SEC since 2008
Grade6.1
◀ Past 5.6● Present 7.3▶ Future 5.1
Who owns Castle Biosciences, Inc.
As filed with the SECHolders of 5% or more
2
RTW Investments, LP holds 9.3% of Common Stock, $0.001 par value, as its SCHEDULE 13G/A filed May 15, 2026 says.
Directors and officers
11
report now, of 17 people on the record since 2019. Their holdings as a group are not read here.
Institutions as a whole
n/a
The record does not read the share held by managers that file Form 13F, so none is printed and no split of the rest is estimated. What it holds is the 2 named at left.
Holders of 5% or moreshare of the class, as filed
RTW Investments, LP
SCHEDULE 13G/A · filed May 15, 2026 · Common Stock, $0.001 par value · 7.2% in Feb 17, 2026
Blackrock, Inc.
SCHEDULE 13G/A · filed Apr 23, 2025 · Common Stock
Portolan Capital Management, LLC
SCHEDULE 13G/A · filed May 15, 2026 · Common Stock, $0.001 par value per share · reported falling below 5%, from 5.65% in Apr 14, 2025
Dimensional Fund Advisors LP
SCHEDULE 13G/A · filed Jan 21, 2026 · Common Stock · reported falling below 5%, from 5.1% in Oct 9, 2025
Wasatch Advisors LP
SCHEDULE 13G/A · filed May 12, 2025 · Common Stock · reported falling below 5%
The Vanguard Group
SCHEDULE 13G/A · filed Mar 26, 2026 · Common Stock · reported falling below 5%, from 6.54% in Jan 30, 2025
What CSTL reports owning in othersstakes of 5% or more, and other ties
Other ties the annual report names
Capsulomics
A company bought · asset acquisition · owns, named in the 10-K filed Feb 26, 2026
4 subsidiaries in 1 country, from the list filed with the 10-K filed Feb 26, 2026.
Insider tradesForm 4
219sales
0purchases
210sales on a scheduled plan
5people selling
$19.0Msold, in dollars
$0bought, in dollars
Open-market trades on Form 4 from Nov 12, 2025 to Nov 12, 2026. A scheduled plan is a selling program set in advance under SEC rule 10b5-1. The trades are listed as filed and do not feed the grade.
By calendar yearSoldBought
2026 runs to Nov 12, 2026. Dollars as filed, summed by the transaction date.
People who traded in the window5 of 25 on the roster
| Person | Role as filed | Sales | Sold | On a plan | Buys | Bought |
|---|---|---|---|---|---|---|
| Maetzold Derek J | Pres. & Chief Exec. Officer | 177 | $11.8M | 177 | 0 | $0 |
| Juvenal Tobin W | Chief Commercial Officer | 23 | $3.4M | 22 | 0 | $0 |
| Oelschlager Kristen M | Chief Operating Officer | 14 | $2.4M | 10 | 0 | $0 |
| Stokes Frank | Chief Financial Officer | 5 | $1.3M | 3 | 0 | $0 |
| Cole G Bradley | director | 2 | $200,000 | 0 | 0 | $0 |