Filing Details

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

The remainder of this cover page shall be filled out for a reporting persons initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

Names of Reporting Persons

Derek J. Maetzold

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☐

SEC Use Only

Citizenship or Place of Organization

United States of America

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With:

Sole Voting Power

871,501⁽¹⁾

Shared Voting Power

150,567⁽²⁾

Sole Dispositive Power

871,501⁽¹⁾

Shared Dispositive Power

150,567⁽²⁾

Aggregate Amount Beneficially Owned by Each Reporting Person

1,022,068⁽¹⁾⁽²⁾

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

4.0%⁽³⁾

Type of Reporting Person (See Instructions)

IN

Includes (a) 301,129 shares of Common Stock, $0.001 par value per share (Common Stock) of Castle Biosciences, Inc. (the Issuer) issuable within 60 days of December 31, 2021 upon the exercise of stock options held directly by Derek J. Maetzold (the Reporting Person); and (b) (i) 127,728 shares of Common Stock held directly by the DJM Grantor Retained Annuity Trust No. 1, (ii) 100,000 shares of Common Stock held directly by the DJM Grantor Retained Annuity Trust No. 2, (iii) 75,000 shares of Common Stock held directly by the DJM Grantor Retained Annuity Trust No. 3 and (iv) 137,965 shares of Common Stock held directly by the Derek Maetzold 2020 Irrevocable Trust (each of which the Reporting Person serves as the sole trustee).

Consists of 150,567 shares of Common Stock held directly by The Maetzold Descendants 2020 Trust, of which the Reporting Persons spouse serves as the sole trustee.

Based upon 25,300,343 shares of Common Stock outstanding as of November 1, 2021, as reported in the Issuers Quarterly Report on Form 10-Q filed on November 8, 2021.

Item 3.

Not Applicable.

Ownership.

Amount beneficially owned:

Percent of class:

Number of shares as to which the person has:

Sole power to vote or to direct the vote: 871,501

Shared power to vote or to direct the vote: 150,567

Sole power to dispose or to direct the disposition of: 871,501

Shared power to dispose or to direct the disposition of: 150,567

Ownership of Five Percent or Less of a Class.

Ownership of More than Five Percent on Behalf of Another Person.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person.

Identification and Classification of Members of the Group.

Notice of Dissolution of Group.

Certifications.