CSTLCastle Biosciences Inc · Insider ownership research

Castle Biosciences Inc insiders sold $19.0M in the past 12 months. How much of their stake is that?

84% was sold under disclosed trading plans, 16% with no plan disclosed. The largest seller, Derek Maetzold (Pres. & Chief Exec. Officer, Director), sold $11.2M. 20% of these sales were shares from exercising options.Share-of-stake figures for this company are being verified and will be added when that check is finished. Why

Updated Oct 16, 2026 from SEC filings · covers Oct 17, 2025 to Oct 16, 2026

$3.0M

sold with no plan disclosed, past 12 months

84%

of sales were under disclosed trading plans, past 12 months

5 of 11

officers and directors sold shares, past 12 months

Is this normal? In line with the past 5 years. 5 insiders sold; the average is 4 a year. Year by year

Latest filing: Filed Oct 14 for a sale on Oct 12. Tobin Juvenal sold 3.3K shares ($111K) under a disclosed plan. Filing

SEC ownership filings: 89 filed in the 12 months to Oct 16, 2026; 578 on record since Jul 24, 2019 · See the evidence

Price note. One filing reports a price of $62,860.00, about 937 times the same filer's other prices that week; it appears to be a decimal error for about $62.86, so we've excluded it from totals. Filing

What stands out

Kristen Oelschlager sold $1.4M of stock with no disclosed trading plan. The filings don't state a reason.Largest such sale, Dec 17, 2025

Selling picked up in the last 90 days: officers and directors sold 261K shares, against an average of 118K per 90 days earlier in the period. Most of it was Derek Maetzold (147K shares in the last 90 days) and Tobin Juvenal (48K shares in the last 90 days); 81% of these sales were under disclosed plans.Derek Maetzold: largest recent sale, Aug 28, 2026 · Tobin Juvenal: largest recent sale, Aug 25, 2026

A share of stake is shown for 0 of the 5 officers and directors who sold. 11 are left out

i

Left out: Derek Maetzold, Kristen Oelschlager, Tobin Juvenal, Frank Stokes, Daniel Bradbury, Ellen Goldberg, Tiffany Olson, Kim Caple, Bradley Cole, Miles Harrison and Rodney Cotton (share of stake is being verified).

Disclosed company stock is not an insider's whole wealth.

Who sold, and how much of their stake

Officers and directors, past 12 months. Their share of stake is being verified and is not shown yet; amounts and trading plans are below.

Derek Maetzold

Pres. & Chief Exec. Officer, Director

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$11.2MDisclosed plan

Kristen Oelschlager

Chief Operating Officer

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$3.3M57% planned 43% no plan disclosed

Tobin Juvenal

Chief Commercial Officer

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$2.8M82% planned 18% no plan disclosed

Frank Stokes

Chief Financial Officer

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$1.5M38% planned 62% no plan disclosed

Bradley Cole

Director

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$211KNo plan disclosed

Amounts, filings and trading plans for each seller

Selling by month

Officers and directors, Oct 2025 to Oct 2026. Each sale is counted once: under a disclosed plan, else to cover taxes, else no plan disclosed.

Disclosed planNo plan disclosedOne dollar scale for every month; the tallest bar is labeled

Recent activity

Past 30 days, Sep 17, 2026 to Oct 16, 2026

Oct 12, 2026Tobin Juvenal sold 3.3K shares ($111K) under a disclosed trading plan.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Tobin Juvenal Chief Commercial Officer	3,288	$33.64	n/a	n/a	Oct 12, 2026	Oct 14, 2026

Oct 5, 2026Derek Maetzold sold 14K shares ($516K) under a disclosed trading plan. 8.2K shares came in from vesting or option exercises the same day, so the holding fell by 6.3K net.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Derek Maetzold Pres. & Chief Exec. Officer, Director	14,496	$35.57	n/a	n/a	Oct 5, 2026	Oct 7, 2026

Oct 1, 2026Kristen Oelschlager sold 4.2K shares ($149K) under a disclosed trading plan. 4.2K shares came in from vesting or option exercises the same day, so the holding rose by 0 net.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Kristen Oelschlager Chief Operating Officer	4,153	$35.95	n/a	n/a	Oct 1, 2026	Oct 5, 2026

Sep 30, 2026Tobin Juvenal sold 1K shares ($35K) under a disclosed trading plan.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Tobin Juvenal Chief Commercial Officer	1,034	$34.20	n/a	n/a	Sep 30, 2026	Oct 1, 2026

Sep 29, 2026Tobin Juvenal sold 5.5K shares ($197K) under a disclosed trading plan.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Tobin Juvenal Chief Commercial Officer	5,543	$35.50	n/a	n/a	Sep 29, 2026	Oct 1, 2026

Show all 6 events

Sep 21, 2026Derek Maetzold sold 14K shares ($512K) under a disclosed trading plan. 8.6K shares came in from vesting or option exercises the same day, so the holding fell by 5.9K net.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Derek Maetzold Pres. & Chief Exec. Officer, Director	14,496	$35.33	n/a	n/a	Sep 21, 2026	Sep 23, 2026

"% of total stake" is the shares in an event against all the vested shares the person held that day, across every share class and holding entity, after that day's vesting. "n/a" means the person's holdings are not confirmed, or the row is a purchase. "Holdings record incomplete" means more shares were sold than the filings show the person held that day, so a percentage would be wrong.

Common questions

Why are Castle Biosciences Inc insiders selling?

Filings rarely give a reason, and we don't guess at one. What they show is how the sales were made: 84% of sales by value ran under 10b5-1 trading plans disclosed in the filings and 16% had no disclosed plan. A trading plan schedules sales in advance.

Are any Castle Biosciences Inc insiders buying?

No. Officers and directors reported no purchases in the past 12 months.

The evidence

Who sold5 officers and directors: amount, % of holdings, trading plan

Who sold	Amount	% of holdings	Trading plan
Derek Maetzold Pres. & Chief Exec. Officer, Director	$11.2M 374K shares	Not confirmed share of stake is being verified. Why	Disclosed plan
Kristen Oelschlager Chief Operating Officer	$3.3M 105K shares	Not confirmed share of stake is being verified. Why	57% under a disclosed plan 43% no plan disclosed
Tobin Juvenal Chief Commercial Officer	$2.8M 89K shares	Not confirmed share of stake is being verified. Why	82% under a disclosed plan 18% no plan disclosed
Frank Stokes Chief Financial Officer	$1.5M 48K shares	Not confirmed share of stake is being verified. Why	38% under a disclosed plan 62% no plan disclosed
Bradley Cole Director	$211K 7.4K shares	Not confirmed share of stake is being verified. Why	No plan disclosed

The full ownership picture0 of 11 officers and directors confirmed

Vested shares across all share classes, held directly and through trusts, LLCs and family members, as reported on SEC Forms 3, 4 and 5. Unvested awards and options are never counted as owned shares.

Insider

Held Oct 16, 2025

Sold

Held Oct 16, 2026

Still held

Derek Maetzold

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Derek Maetzold are complete.

Pres. & Chief Exec. Officer, Director

n/a

−374K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Derek Maetzold

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Derek Maetzold are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−56Kwithheld by the company for taxes

Kristen Oelschlager

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. See the filing Sales and other transactions for Kristen Oelschlager are complete.

Chief Operating Officer

n/a

−105K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Kristen Oelschlager

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Kristen Oelschlager are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−16Kwithheld by the company for taxes

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
8,305	$3.38	Mar 12, 2029	$251K

Estimate: options held × ($33.64 − strike price), using the most recent insider trade price on Form 4 (Oct 12, 2026), not a market close.

Tobin Juvenal

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. See the filing Sales and other transactions for Tobin Juvenal are complete.

Chief Commercial Officer

n/a

−89K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Tobin Juvenal

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Tobin Juvenal are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−23Kwithheld by the company for taxes

Frank Stokes

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Frank Stokes are complete.

Chief Financial Officer

n/a

−48K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Frank Stokes

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Frank Stokes are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−24Kwithheld by the company for taxes

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
14,912	$3.38	Mar 12, 2029	$451K

Estimate: options held × ($33.64 − strike price), using the most recent insider trade price on Form 4 (Oct 12, 2026), not a market close.

Daniel Bradbury

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Daniel Bradbury are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Daniel Bradbury

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Daniel Bradbury are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Ellen Goldberg

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Ellen Goldberg are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Ellen Goldberg

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Ellen Goldberg are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Tiffany Olson

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Tiffany Olson are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Tiffany Olson

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Tiffany Olson are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
3,379	$71.22	Jul 1, 2034	$0

Estimate: options held × ($33.64 − strike price), using the most recent insider trade price on Form 4 (Oct 12, 2026), not a market close.

Kim Caple

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Kim Caple are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Kim Caple

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Kim Caple are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Bradley Cole

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Bradley Cole are complete.

Director

n/a

−7.4K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Bradley Cole

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Bradley Cole are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
20,000	$3.38	Mar 11, 2029	$605K

Estimate: options held × ($33.64 − strike price), using the most recent insider trade price on Form 4 (Oct 12, 2026), not a market close.

Miles Harrison

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Miles Harrison are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Miles Harrison

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Miles Harrison are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Rodney Cotton

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Rodney Cotton are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Rodney Cotton

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Rodney Cotton are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Holdings and share of stake for Castle Biosciences Inc are being verified, so no balances, unit counts or percentages are shown. Sales, proceeds, plan and tax status, titles and dates come straight from individual filings.

What explains the selling$19.0M of sales by plan status, purpose, seller and month

Officer and director open-market sales: $19.0M across 622,856 shares. Plan status and stated purpose are separate questions, and a sale can have both.

By plan status

Disclosed plan · $16.0M · 84%

16%

The lighter segment is sales with no plan disclosed in the filing ($3.0M), including tax-related sales outside a plan.

No plan disclosed · $3.0M

Sales with no 10b5-1 plan and no tax reference in the filing. $1.4M of it is Kristen Oelschlager. No plan disclosed is a statement about the filing, not about why the sale happened. Largest such sale: Frank Stokes, Aug 14, 2026

Taxes

119,368 shares ($3.8M) were withheld by the company for taxes, which isn't a market sale.

Seller	Shares sold	Proceeds	Under a disclosed plan	Share of total	Sales dates
Derek Maetzold Pres. & Chief Exec. Officer, Director	374K	$11.2M	100%	59%	Oct 20, 2025 to Oct 5, 2026
Kristen Oelschlager Chief Operating Officer	105K	$3.3M	57%	18%	Oct 31, 2025 to Oct 1, 2026
Tobin Juvenal Chief Commercial Officer	89K	$2.8M	82%	15%	Nov 11, 2025 to Oct 12, 2026
Frank Stokes Chief Financial Officer	48K	$1.5M	38%	8%	Nov 11, 2025 to Aug 14, 2026
Bradley Cole Director	7.4K	$211K	0%	1%	Mar 5, 2026 to Mar 5, 2026

Sales by month

Month	Sale proceeds	Disclosed plan	To cover taxes	No plan disclosed
Oct 2025	$348K	$348K	$0	$0
Nov 2025	$1.9M	$1.9M	$0	$0
Dec 2025	$2.7M	$1.5M	$0	$1.2M
Jan 2026	$316K	$316K	$0	$0
Feb 2026	$159K	$159K	$0	$0
Mar 2026	$3.6M	$3.4M	$0	$211K
Apr 2026	$351K	$351K	$0	$0
May 2026	$302K	$302K	$0	$0
Jun 2026	$469K	$469K	$0	$0
Jul 2026	$1.6M	$1.6M	$0	$0
Aug 2026	$4.9M	$3.3M	$0	$1.6M
Sep 2026	$1.6M	$1.6M	$0	$0
Oct 2026	$775K	$775K	$0	$0

Is this normal? Selling year by year5 earlier years to compare with

In line with the past 5 years. 5 insiders sold; the average is 4 a year.

12 months ending	Shares sold	Insiders who sold	Proceeds
Oct 16, 2026 Latest 12 months	623K	5	$19.0M
Oct 16, 2025 1 year earlier	270K	5	$6.6M
Oct 16, 2024 2 years earlier	448K	4	$10.1M
Oct 17, 2023 3 years earlier	347K	2	$7.8M
Oct 17, 2022 4 years earlier	283K	2	$11.2M
Oct 17, 2021 5 years earlier	1.97M	8	$131M

Open-market sales (Form 4 code S) by people who were officers or directors, in split-adjusted shares. Earlier years include people who have since left. A sale that an outside holder also reports (a family trust, a fund) is counted with outside holders in every year. Shares, not dollars, are compared, so a change in the stock price doesn't look like a change in selling. Years the filings don't fully cover are shown but left out of the average.

Known gaps and uncertainty11 officers and directors not confirmed

Holdings and share of stake are being verified. Balances, unit counts and every share-of-stake figure for Castle Biosciences Inc are held back until that check is finished. Sales, proceeds, plan and tax status, titles and dates come straight from individual filings and are complete.

External context: we only cite outside events when a documented connection exists. None is shown for this period.

Sources and methodology578 filings on record, 89 filed in the 12-month period, and how we read them

All 578 Forms 3, 4 and 5 on record for Castle Biosciences Inc (SEC CIK 1447362), filed from Jul 24, 2019 to Oct 14, 2026; 89 of them were filed in the 12 months this page covers, retrieved from SEC EDGAR on Oct 16, 2026. Prices are the ones reported in each filing, often weighted averages.

Holdings. Each holding line (a share class plus an owner, such as a trust or LLC) carries its last reported balance forward. Entities first reported during the period start at zero, so transfers between an insider's own trusts don't count as selling. Lines not reported for three years or more are listed separately and left out of totals.

Sales. A sale counts as under a 10b5-1 plan if its footnote cites one or the filing's Rule 10b5-1 box is checked, and as tax-related if its footnote cites tax obligations or sell-to-cover. Shares withheld by the company for taxes are listed separately. Sales with neither attribute are labeled "no plan disclosed".

Full methodology

Former or inactive filers (9)No filing in 18 months; last reported balances, not in any total

Name	Last filed	Last reported balance
Mara Aspinall	Jun 4, 2024	44,139 shares, last reported balance as of May 23, 2024
Bernhard Spiess	Dec 14, 2021	14,696 shares, last reported balance as of Dec 10, 2021
David Kabakoff	Jun 21, 2021	503,577 shares, last reported balance as of Jun 17, 2021
Joseph Cook III	Mar 22, 2021	2,223,082 shares, last reported balance as of Mar 18, 2021
Joseph Cook III	Mar 22, 2021	628,410 shares, last reported balance as of Mar 18, 2021
Bonnie Anderson	Jul 28, 2020	45,353 shares, last reported balance as of Jul 16, 2020
Federico Monzon	May 26, 2020	31,459 shares, last reported balance as of May 22, 2020
MGC Venture Partners 2013 GP, LLC	May 19, 2020	3,210,875 shares, last reported balance as of May 15, 2020
Sofinnova HealthQuest Partners, L.P.	May 19, 2020	1,433,577 shares, last reported balance as of May 12, 2020

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