Item 5. Other Information
Item 5. Other Information.
Insider Trading Arrangements
On March 9, 2026 , Frank Stokes , our Chief Financial Officer , adopted a Rule 10b5-1 trading arrangement providing for the sale from time to time of an aggregate of up to 29,421 shares of our common stock. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c). The duration of the trading arrangement is estimated to be from June 8, 2026 until the earlier of all transaction under the trading arrangement being completed or June 30, 2026 .
No other officers or directors, as defined in Rule 16a-1(f), adopted and/or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement, as defined in Regulation S-K Item 408, for the three months ended March 31, 2026.
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Item 6. Exhibits.
Exhibit Number Description
3.1 Amended and Restated Certificate of Incorporation of the Registrant, incorporated by reference to Exhibit 3.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on May 23, 2025.
3.2 Amended and Restated Bylaws of the Registrant, incorporated by reference to Exhibit 3.1 of the Registrant’s Current Report on Form 8-K filed with the SEC on August 8, 2025.
4.1 Form of Common Stock Certificate of the Registrant, incorporated by reference to Exhibit 4.1 of the Registrant’s Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on June 26, 2019.
10.1*
First Amendment to Office Lease Agreement, dated March 5, 2026, by and between the Registrant and Perimeter Gateway Portfolio LLC.
10.2* †
Lease Agreement, dated March 19, 2026, by and between the Registrant and Faros ACA RE LLC.
10.3* †
Second Amendment to Lease Agreement, dated March 19, 2026, by and between the Registrant and ACA Concourse East Unit 3 LLC.
31.1* Certification of Principal Executive Officer pursuant to Rules 13a-14(a) and 15d-14(a) of the Exchange Act.
31.2* Certification of Principal Financial Officer pursuant to Rules 13a-14(a) and 15d-14(a) of the Exchange Act.
32.1** Certification of Principal Executive Officer and Principal Financial Officer pursuant to Rules 13a-14(b) or 15d-14(b) of the Exchange Act, and 18 U.S.C. Section 1350.
101.INS* Inline XBRL Instance Document—the instance document does not appear in the Interactive Data File as its XBRL tags are embedded within the Inline XBRL document.
101.SCH* Inline XBRL Taxonomy Extension Schema.
101.CAL* Inline XBRL Taxonomy Extension Calculation Linkbase.
101.DEF* Inline XBRL Taxonomy Extension Definition Linkbase.
101.LAB* Inline XBRL Taxonomy Extension Label Linkbase.
101.PRE* Inline XBRL Taxonomy Extension Presentation Linkbase.
104* Cover Page Interactive Data File (embedded within the Inline XBRL and contained in Exhibit 101).
* Filed herewith
** Furnished herewith
† Certain schedules or exhibits have been omitted pursuant to Item 601(a)(5) of Regulation S-K. A copy of any omitted schedule or exhibit will be furnished to the SEC upon request; provided, however, that we may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any schedule or exhibit so furnished.
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SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.
CASTLE BIOSCIENCES, INC.
Date: May 6, 2026 By: /s/ Derek J. Maetzold
Derek J. Maetzold
President and Chief Executive Officer
(Principal Executive Officer)
Date: May 6, 2026 By: /s/ Frank Stokes
Frank Stokes
Chief Financial Officer
(Principal Financial and Accounting Officer)
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