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person · Reporting owner

MAETZOLD DEREK J

Disclosed activity across 1 company

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17918
SEC CIK
0001239501

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Reported relationships

Latest disclosed role at each company.

CompanyLast reported asReport datePublished
CASTLE BIOSCIENCES INCCSTL · Entity 359Director · Pres. & Chief Exec. OfficerOctober 05, 2026October 07, 2026

Disclosed balances

About these balances

Latest available filing per company, not a reconstructed current portfolio. Matching sequences show the last reported balance with all source rows expandable; grouping alone does not establish account ownership. Do not add unresolved positions together. Filings may omit unchanged positions, and amendments may correct only part of an older disclosure. Jointly reported shares are not necessarily this owner's personal holdings.

CASTLE BIOSCIENCES INC

Report date October 05, 2026 · Filed October 07, 2026

Security / awardOwnership accountDisclosed shares / unitsDisclosure context
Common StockSEC Table I · non-derivativeDirect21,064 Ending reported balance After 2026-10-05 transaction · row 2
2 source rows · reconciled sequence

Row 1 · 2026-10-05 · Exercise / conversion · Acquired 8,165 · Balance 29,644

F1: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.

Row 2 · 2026-10-05 · Sale · Disposed 8,580 · Balance 21,064

F1: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.

F2: This transaction was executed in multiple trades at prices ranging from $35.310 to $35.965, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Common StockSEC Table I · non-derivativeIndirectBy The Maetzold Descendants 2020 Trust8,038 Reported balance After 2026-10-05 transaction · row 3 Account identity is unresolved; indirect or unspecified ownership is not merged.
1 source row

Row 3 · 2026-10-05 · Sale · Disposed 3,198 · Balance 8,038

F1: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.

F2: This transaction was executed in multiple trades at prices ranging from $35.310 to $35.965, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Common StockSEC Table I · non-derivativeIndirectBy Derek Maetzold 2020 Irrevocable Trust6,832 Reported balance After 2026-10-05 transaction · row 4 Account identity is unresolved; indirect or unspecified ownership is not merged.
1 source row

Row 4 · 2026-10-05 · Sale · Disposed 2,718 · Balance 6,832

F1: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.

F2: This transaction was executed in multiple trades at prices ranging from $35.310 to $35.965, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Stock option (right to buy)SEC Table II · derivative / convertible security · Conversion / exercise price $2.39 · Expires 2028-05-09Direct0 Reported balance After 2026-10-05 transaction · row 13 Instrument identity requires review; Table II rows are not merged.
1 source row

Row 13 · 2026-10-05 · Exercise / conversion · Disposed 8,165 · Balance 0

F1: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.

F13: The shares subject to the option are fully vested.

Common StockSEC Table I · non-derivativeIndirectBy The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk11,256 Reported balance Holding disclosure · report date 2026-10-05 · row 5 Holding and transaction disclosures are not merged.
1 source row

Row 5 · Balance 11,256

F5: Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.

Common StockSEC Table I · non-derivativeIndirectBy The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold11,256 Reported balance Holding disclosure · report date 2026-10-05 · row 6 Holding and transaction disclosures are not merged.
1 source row

Row 6 · Balance 11,256

F6: Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Common StockSEC Table I · non-derivativeIndirectBy The Maetzold 2018 Remainder Trust FBO John Derek Maetzold11,256 Reported balance Holding disclosure · report date 2026-10-05 · row 7 Holding and transaction disclosures are not merged.
1 source row

Row 7 · Balance 11,256

F7: Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Common StockSEC Table I · non-derivativeIndirectBy The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold11,256 Reported balance Holding disclosure · report date 2026-10-05 · row 8 Holding and transaction disclosures are not merged.
1 source row

Row 8 · Balance 11,256

F8: Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Common StockSEC Table I · non-derivativeIndirectBy DJM Grantor Retained Annuity Trust No. 611,963 Reported balance Holding disclosure · report date 2026-10-05 · row 9 Holding and transaction disclosures are not merged.
1 source row

Row 9 · Balance 11,963

F9: Held by DJM Grantor Retained Annuity Trust No. 6 of which the Reporting Person is the trustee and the beneficiaries are The Maetzold 2018 Remainder Trust FBO John Derek Maetzold, The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk, The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold and The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold.

Common StockSEC Table I · non-derivativeIndirectBy DJM Grantor Retained Annuity Trust No. 727,862 Reported balance Holding disclosure · report date 2026-10-05 · row 10 Holding and transaction disclosures are not merged.
1 source row

Row 10 · Balance 27,862

F10: Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary.

Common StockSEC Table I · non-derivativeIndirectBy DJM Grantor Retained Annuity Trust No. 840,935 Reported balance Holding disclosure · report date 2026-10-05 · row 11 Holding and transaction disclosures are not merged.
1 source row

Row 11 · Balance 40,935

F11: Held by DJM Grantor Retained Annuity Trust No. 8 of which the Reporting Person is the trustee and beneficiary.

Common StockSEC Table I · non-derivativeIndirectDJM Grantor Retained Annuity Trust No. 923,216 Reported balance Holding disclosure · report date 2026-10-05 · row 12 Holding and transaction disclosures are not merged.
1 source row

Row 12 · Balance 23,216

F12: Held by DJM Grantor Retained Annuity Trust No. 9 of which the Reporting Person is the trustee and beneficiary.

Filing footnotes · ownership attribution and instrument terms

F1: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.

F2: This transaction was executed in multiple trades at prices ranging from $35.310 to $35.965, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

F4: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

F5: Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.

F6: Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

F7: Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

F8: Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

F9: Held by DJM Grantor Retained Annuity Trust No. 6 of which the Reporting Person is the trustee and the beneficiaries are The Maetzold 2018 Remainder Trust FBO John Derek Maetzold, The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk, The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold and The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold.

F10: Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary.

F11: Held by DJM Grantor Retained Annuity Trust No. 8 of which the Reporting Person is the trustee and beneficiary.

F12: Held by DJM Grantor Retained Annuity Trust No. 9 of which the Reporting Person is the trustee and beneficiary.

F13: The shares subject to the option are fully vested.

Transaction history

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Purchases/sales include open-market and private transactions. Plan disclosure applies to the filing; individual rows may differ. “Not disclosed” is not “unplanned.”

The cutoff filters transaction history only. Company summaries and owner relationships show the latest available disclosures. Parser corrections can improve historical records.

Transaction dateCompanyActivity / securityShares / unitsReported priceReported valueDetails
August 04, 2026 Filed Aug 6, 2026 20:14 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 4,782 $31.34 $149,848.75
Disclosure

SEC source: 0001628280-26-054334 · wk-form4_1786047267.xml · nonDerivative · entry 6

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 23,625

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F5 · price: This transaction was executed in multiple trades at prices ranging from $31.010 to $31.650, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
August 04, 2026 Filed Aug 6, 2026 20:14 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 11,935 $31.34 $373,995.16
Disclosure

SEC source: 0001628280-26-054334 · wk-form4_1786047267.xml · nonDerivative · entry 5

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,479

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F5 · price: This transaction was executed in multiple trades at prices ranging from $31.010 to $31.650, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
August 04, 2026 Filed Aug 6, 2026 20:14 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 2,866 $30.79 $88,238.41
Disclosure

SEC source: 0001628280-26-054334 · wk-form4_1786047267.xml · nonDerivative · entry 4

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 24,143

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.995, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Read SEC document
August 04, 2026 Filed Aug 6, 2026 20:14 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 3,374 $30.79 $103,878.71
Disclosure

SEC source: 0001628280-26-054334 · wk-form4_1786047267.xml · nonDerivative · entry 3

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 28,407

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.995, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
August 04, 2026 Filed Aug 6, 2026 20:14 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 8,421 $30.79 $259,265.75
Disclosure

SEC source: 0001628280-26-054334 · wk-form4_1786047267.xml · nonDerivative · entry 2

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 33,414

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.995, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
August 04, 2026 Filed Aug 6, 2026 20:14 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionCommon Stock 20,356 $2.39 $48,650.84
Disclosure

SEC source: 0001628280-26-054334 · wk-form4_1786047267.xml · nonDerivative · entry 1

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 41,835

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

Read SEC document
August 03, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionStock option (right to buy) · Derivative 10,664 $0.00 Strike: $2.39 $0.00
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · derivative · entry 18

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 61,759

Underlying: Common Stock · 10,664 shares

Expires 2028-05-09

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F15 · derivative.exercise_date: The shares subject to the option are fully vested.

Read SEC document
August 03, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 3,597 $30.35 $109,179.74
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 8

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 27,009

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F6 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F5 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Read SEC document
August 03, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 4,232 $30.35 $128,453.90
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 7

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 31,781

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F6 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
August 03, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 10,664 $30.35 $323,684.39
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 6

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,479

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F6 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
August 03, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionCommon Stock 10,664 $2.39 $25,486.96
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 5

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 32,143

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

Read SEC document
July 31, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionStock option (right to buy) · Derivative 6,480 $0.00 Strike: $2.39 $0.00
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · derivative · entry 17

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 72,423

Underlying: Common Stock · 6,480 shares

Expires 2028-05-09

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F15 · derivative.exercise_date: The shares subject to the option are fully vested.

Read SEC document
July 31, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,690 $30.15 $50,956.88
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 4

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 30,606

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F3 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F5 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Read SEC document
July 31, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,983 $30.15 $59,791.42
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 3

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 36,013

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F3 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
July 31, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 6,480 $30.15 $195,384.96
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 2

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,479

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F3 · price: This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
July 31, 2026 Filed Aug 4, 2026 20:35 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionCommon Stock 6,480 $2.39 $15,487.20
Disclosure

SEC source: 0001628280-26-052647 · wk-form4_1785875751.xml · nonDerivative · entry 1

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 27,959

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · balance_after: Reflects the July 30, 2026 transfers of 6,755 shares of common stock from DJM Grantor Retained Annuity Trust No. 6 and 16,461 shares from DJM Grantor Retained Annuity Trust No. 7 to the Reporting Person's direct holdings, followed by the transfer of those shares to DJM Grantor Retained Annuity Trust No. 9.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionStock option (right to buy) · Derivative 6,214 $0.00 Strike: $2.39 $0.00
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · derivative · entry 19

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 78,903

Underlying: Common Stock · 6,214 shares

Expires 2028-05-09

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F13 · derivative.exercise_date: The shares subject to the option are fully vested.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 10 $25.06 $250.60
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 15

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold

Disclosed balance after: 11,812

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F8 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 10 $25.06 $250.60
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 14

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold

Disclosed balance after: 11,812

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F7 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 10 $25.06 $250.60
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 13

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold

Disclosed balance after: 11,812

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F6 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

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July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 10 $25.06 $250.60
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 12

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk

Disclosed balance after: 11,812

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F5 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 43 $25.06 $1,077.58
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 11

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 32,296

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 50 $25.06 $1,253.00
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 10

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 37,996

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 232 $25.06 $5,813.92
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 9

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,479

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F9 · price: This transaction was executed in multiple trades at prices ranging from $24.97 to $25.11, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 268 $24.13 $6,466.84
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 8

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold

Disclosed balance after: 11,822

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F8 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 268 $24.13 $6,466.84
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 7

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold

Disclosed balance after: 11,822

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F7 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 268 $24.13 $6,466.84
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 6

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold

Disclosed balance after: 11,822

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F6 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 268 $24.13 $6,466.84
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 5

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk

Disclosed balance after: 11,822

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F5 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,110 $24.13 $26,784.30
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 4

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 32,339

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,307 $24.13 $31,537.91
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 3

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 38,046

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 5,982 $24.13 $144,345.66
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 2

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,711

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.85 to $24.62, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
July 27, 2026 Filed Jul 29, 2026 20:09 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionCommon Stock 6,214 $2.39 $14,851.46
Disclosure

SEC source: 0001628280-26-050616 · wk-form4_1785355793.xml · nonDerivative · entry 1

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 27,693

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionStock option (right to buy) · Derivative 550 $0.00 Strike: $2.39 $0.00
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · derivative · entry 12

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 85,117

Underlying: Common Stock · 550 shares

Expires 2028-05-09

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F12 · derivative.exercise_date: The shares subject to the option are fully vested.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $22.92 $6,371.76
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 8

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold

Disclosed balance after: 12,090

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F8 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $22.92 $6,371.76
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 7

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold

Disclosed balance after: 12,090

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F7 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $22.92 $6,371.76
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 6

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold

Disclosed balance after: 12,090

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F6 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $22.92 $6,371.76
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 5

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk

Disclosed balance after: 12,090

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F5 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,153 $22.92 $26,426.76
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 4

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 33,449

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,357 $22.92 $31,102.44
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 3

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 39,353

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 550 $22.92 $12,606.00
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 2

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,479

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $22.62 to $23.15, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Read SEC document
July 14, 2026 Filed Jul 16, 2026 20:16 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionCommon Stock 550 $2.39 $1,314.50
Disclosure

SEC source: 0001628280-26-048461 · wk-form4_1784232967.xml · nonDerivative · entry 1

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 22,029

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

Read SEC document
July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionStock option (right to buy) · Derivative 6,214 $0.00 Strike: $2.39 $0.00
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · derivative · entry 12

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 85,667

Underlying: Common Stock · 6,214 shares

Expires 2028-05-09

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F12 · derivative.exercise_date: The shares subject to the option are fully vested.

Read SEC document
July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $24.29 $6,752.62
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 8

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold

Disclosed balance after: 12,368

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F8 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $24.29 $6,752.62
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 7

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold

Disclosed balance after: 12,368

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F7 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $24.29 $6,752.62
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 6

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold

Disclosed balance after: 12,368

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F6 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.

Read SEC document
July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 278 $24.29 $6,752.62
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 5

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk

Disclosed balance after: 12,368

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F5 · ownership.nature: Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.

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July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,153 $24.29 $28,006.37
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 4

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By Derek Maetzold 2020 Irrevocable Trust

Disclosed balance after: 34,602

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F4 · ownership.nature: Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

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July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 1,357 $24.29 $32,961.53
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 3

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Indirect · By The Maetzold Descendants 2020 Trust

Disclosed balance after: 40,710

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F3 · ownership.nature: Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.

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July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 SaleCommon Stock 6,214 $24.29 $150,938.06
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 2

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 21,479

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

F2 · price: This transaction was executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

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July 01, 2026 Filed Jul 6, 2026 20:25 UTC CASTLE BIOSCIENCES INC CSTL · Entity 359 Exercise / conversionCommon Stock 6,214 $2.39 $14,851.46
Disclosure

SEC source: 0001628280-26-047287 · wk-form4_1783369520.xml · nonDerivative · entry 1

MAETZOLD DEREK J · CIK 0001239501 · Director · Pres. & Chief Exec. Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 27,693

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.

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Value uses the disclosed total when available, otherwise shares × reported transaction price. It is not an estimate of exercise cash cost or investment performance.