Castle Biosciences CSTL Insider Ownership

NASDAQ CSTL

$33.79 -0.71 (-2.06%)

At close: Nov 13, 2026 · 4:00 PM EST

Insider Holdings by Owner

379.03K Shares

Mara G. Aspinall44.14K11.6%

Ellen Goldberg40.92K10.8%

Tiffany Olson39.57K10.4%

Tobin W Juvenal38.85K10.3%

Kim Caple36.12K9.5%

Other insiders (7)179.42K47.3%

Insider Ownership Statistics

as of 30 Sep, 2026

Insider Ownership

1.67%

▼-0.574% pp QoQ

Shares Held by Insiders

508.97K

filed for Sep 2026

▼-25.61% QoQ

Shares Outstanding

30.51Mn

30,508,534 shares

Direct Holdings

362.58K

Indirect: 146.39K

Net Open-Market Trades

-261.87K

net sold · -$8.08Mn in Sep 2026

Insiders Holding Shares

with Form 4 holdings on file

Shares Owned by Insiders

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Open-Market Insider Trades

Bought Sold

Latest quarter —

Net over range —

Net-buying quarters —

Insider Ownership Summary

Updated Nov 13, 2026

Across the past 12 months, open-market trades by Castle Biosciences insiders were all sales, totaling $18.76 million (612K shares).

Counted by insider, open-market selling of CSTL stock in the past 12 months came from 5 insiders, with no insider buying.
The largest open-market sales of CSTL in the past 12 months were by Derek J. Maetzold (President & Chief Executive Officer), totaling $11.85 million (392K shares), most recently on November 2, 2026.
Away from the open market, CSTL insiders received 79.55K shares in stock awards, acquired 365.38K shares through option exercises and conversions and gave up 119.37K shares to cover taxes or exercise prices over the last 12 months.
Per Business Quant data, Castle Biosciences insiders hold 460.49K shares in total based on their latest Form 4 filings, down 32.70% from 684.21K shares at the end of Q2 2026.
Of the 460.49K shares held by Castle Biosciences insiders, 331.85K shares (72.06%) are held directly and 128.64K shares (27.94%) indirectly, through trusts, partnerships, family members and other entities.
Per Business Quant, 11 insiders of CSTL hold shares, counting officers, directors and 10% owners who have filed a Form 4 in the past two years.
CSTL's three largest insider shareholders, per their latest Form 4 filings, are Kristen M. Oelschlager (Chief Operating Officer, 86K shares), Derek J. Maetzold (President & Chief Executive Officer, 51.97K shares) and Tobin W. Juvenal (Chief Commercial Officer, 41.08K shares).
The holding of Kristen M. Oelschlager makes up 18.68% of all shares held by Castle Biosciences insiders.
Institutional investors held 89.58% of Castle Biosciences stock at the end of Q2 2026, while the latest Form 4 filings of its insiders account for about 1.51%; other investors, including the public, hold roughly 8.91%.
Over the past 12 months, 11 insiders reported transactions in Castle Biosciences stock in 79 Form 4 filings.
The insider holdings and trades above for Castle Biosciences reflect Form 4 filings through November 4, 2026.

Form 4 Holdings

Insiders Holding CSTL

Insiders 12

Shares held 379.03K

Of outstanding 1.24%

#	Insider	Position	Direct	Indirect	Total	Share of Insiders	Last Filed
1	Mara G. Aspinall	Director	44,139	0	44,139	11.6%	04 Jun, 2024
2	Ellen Goldberg	Director	40,921	0	40,921	10.8%	27 May, 2025
3	Tiffany Olson	Director	39,573	0	39,573	10.4%	27 May, 2025
4	Tobin W Juvenal	Chief Commercial Officer	38,853	0	38,853	10.3%	30 Oct, 2026
5	Kim Caple	Director	36,121	0	36,121	9.5%	27 May, 2025
6	Miles Harrison	Director	35,631	0	35,631	9.4%	27 May, 2025
7	Frank Stokes	Chief Financial Officer	35,177	0	35,177	9.3%	18 Aug, 2026
8	Rodney Cotton	Director	32,998	0	32,998	8.7%	27 May, 2025
9	G Bradley Cole	Director	32,976	0	32,976	8.7%	27 May, 2026
10	Daniel Bradbury	Director	22,340	0	22,340	5.9%	27 May, 2025
11	Kristen M Oelschlager	Chief Operating Officer	13,356	0	13,356	3.5%	05 Oct, 2026
12	Derek J Maetzold	Pres. Chief Exec. Officer	3,904	3,038	6,942	1.8%	04 Nov, 2026

Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.

Form 4 Filings

2,982 Insider Transactions

Source SEC Form 4

Latest quarter Sep 2026

Date	Insider	Position	Transaction	Shares	Price	Value	Shares Held After	Ownership
02 Nov, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	7,555	$36.01	$272.02K	4,929	Direct
02 Nov, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	2,816	$36.01	$101.39K	2,024	Indirect
02 Nov, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	2,393	$36.01	$86.16K	1,721	Indirect
02 Nov, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	1,025	$36.81	$37.73K	3,904	Direct
02 Nov, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	382	$36.81	$14.06K	1,642	Indirect
02 Nov, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	325	$36.81	$11.96K	1,396	Indirect
28 Oct, 2026	Tobin W Juvenal	Chief Commercial Officer	Disposed S	1,237	$35.58	$44.01K	44,194	Direct
28 Oct, 2026	Tobin W Juvenal	Chief Commercial Officer	Disposed S	5,341	$36.62	$195.58K	38,853	Direct
26 Oct, 2026	Tobin W Juvenal	Chief Commercial Officer	Disposed S	3,288	$33.08	$108.77K	45,431	Direct
19 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	8,580	$31.91	$273.79K	12,484	Direct
19 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	3,198	$31.91	$102.05K	4,840	Indirect
19 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	2,718	$31.91	$86.73K	4,114	Indirect
12 Oct, 2026	Tobin W Juvenal	Chief Commercial Officer	Disposed S	3,288	$33.64	$110.61K	48,719	Direct
05 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Acquired M	8,165	$2.39	$19.51K	29,644	Direct
05 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	8,580	$35.57	$305.16K	21,064	Direct
05 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	3,198	$35.57	$113.74K	8,038	Indirect
05 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed S	2,718	$35.57	$96.67K	6,832	Indirect
05 Oct, 2026	Derek J Maetzold	Pres. Chief Exec. Officer	Disposed M	8,165	$0.00	$0	0	Direct
01 Oct, 2026	Kristen M Oelschlager	Chief Operating Officer	Acquired M	4,153	$3.38	$14.04K	17,509	Direct
01 Oct, 2026	Kristen M Oelschlager	Chief Operating Officer	Disposed S	2,807	$35.75	$100.35K	14,702	Direct

Showing 1 to 20 of 2,982 transactions