Kristen M. Oelschlager - 01 Sep 2026 Form 4 Insider Report for CASTLE BIOSCIENCES INC (CSTL)

Reporting relationship: Chief Operating Officer
Issuer ticker: CSTL
Reported as of: 01 Sep 2026
Net transaction value: -$138,643
SEC form: 4
Accepted by SEC: 03 Sep 2026, 16:07:34 UTC
Prior SEC filing: 26 Aug 2026
Source filing: View source filing
Reporting owner signature: /s/ Frank Stokes, Attorney-in-fact

Key filing fact

Kristen M. Oelschlager filed Form 4 for CASTLE BIOSCIENCES INC (CSTL) on 03 Sep 2026.

Key facts

This page summarizes Kristen M. Oelschlager's Form 4 filing for CASTLE BIOSCIENCES INC (CSTL).
4 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 03 Sep 2026, 16:07.

Change

Previous filing in this sequence was filed on 26 Aug 2026.
Current net transaction value: -$138,643.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001856565 Primary reporting owner

Oelschlager Kristen M

Relationship: Chief Operating Officer
Address: C/O CASTLE BIOSCIENCES, INC., 1500 W. PARKWOOD AVE SUITE 400, FRIENDSWOOD
Signature: /s/ Frank Stokes, Attorney-in-fact
Signature date: 03 Sep 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

CSTL transaction

Common Stock

Options Exercise

Transaction value
Shares: +4,152
Change %: +31%
Price: $3.38^*
Shares after: 17,508
Date: 01 Sep 2026
Ownership: Direct
Footnotes: F1, F2

CSTL transaction

Common Stock

Sale

Transaction value: $131,839
Shares: -3,952
Change %: -23%
Price: $33.36
Shares after: 13,556
Date: 01 Sep 2026
Ownership: Direct
Footnotes: F1, F3

CSTL transaction

Common Stock

Sale

Transaction value: $6,804
Shares: -200
Change %: -1.5%
Price: $34.02
Shares after: 13,356
Date: 01 Sep 2026
Ownership: Direct
Footnotes: F1

CSTL holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 72,649
Date: 01 Sep 2026
Ownership: The Fritz Shorter Trust
Footnotes: F4

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

CSTL transaction Derivative

Stock option (right to buy)

Options Exercise

Transaction value
Shares: -4,152
Change %: -25%
Price: $0.000000^*
Shares after: 12,458
Date: 01 Sep 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 4,152
Exercise price: $3.38
Footnotes: F1, F5

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 5 footnotes

Footnote F1

These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person, on March 17, 2026.

Footnote F2

Includes 68 shares acquired on August 31, 2026, under the Issuer's employee stock purchase plan.

Footnote F3

This transaction was executed in multiple trades at prices ranging from $33.015 to $33.900, 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.

Footnote F4

Held by the Fritz Shorter Trust of which the Reporting Person and her spouse are the trustees and beneficiaries.

Footnote F5

The shares subject to the option are fully vested.