[Form 4] Castle Biosciences, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Kristen M. Oelschlager, Chief Operating Officer of Castle Biosciences (CSTL), reported the sale of 12,677 shares of the company's common stock in a transaction executed at a weighted-average price of $22.019 per share. The reported sale was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person and, after the transaction, the reporting person beneficially owned 141,116 shares. The filing discloses that the sale occurred in multiple trades at prices ranging from $22.000 to $22.145 and that the reporting person will provide detailed trade-level information on request.

Positive

• Transaction executed under a Rule 10b5-1 plan, indicating trades were pre-scheduled and aiming to reduce potential timing concerns
• Weighted-average price and price range disclosed, and the reporting person offers to provide detailed trade-level information on request, enhancing transparency
• Reporting person retains a meaningful stake after the sale (141,116 shares), so control was not surrendered

Negative

• None.

Insights

Securities Analyst

TL;DR: Insider executed a planned sale under a 10b5-1 plan; transaction size appears routine relative to disclosed post-sale holdings.

The sale of 12,677 shares at a weighted-average $22.019 was executed under a pre-established Rule 10b5-1 plan, which typically indicates the trades were scheduled in advance to avoid timing concerns. The filing states the trades occurred across a narrow price range and that the reporting person retains 141,116 shares following the disposition. From a market-impact perspective, the disclosure promotes transparency but does not by itself indicate material change to company control or governance.

Corporate Governance Expert

TL;DR: Use of a 10b5-1 plan and offer to provide trade details signals compliance and governance transparency.

Reporting the disposition and citing a Rule 10b5-1 plan aligns with governance best practices by documenting the affirmative defense for scheduled trades. The filer’s offer to supply trade-level data on request increases disclosure quality. The filing does not report any derivative transactions or other changes in indirect ownership, and it was signed by an attorney-in-fact, consistent with authorized reporting procedures.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Oelschlager Kristen M

(Last) (First) (Middle)

C/O CASTLE BIOSCIENCES, INC.

505 S FRIENDSWOOD DRIVE, SUITE 401

(Street)

FRIENDSWOOD TX 77546

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
CASTLE BIOSCIENCES INC [ CSTL ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Operating Officer

3. Date of Earliest Transaction (Month/Day/Year)
08/27/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/27/2025		S(1)		12,677	D	$22.019(2)	141,116	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person, on March 6, 2025

2. This transaction was executed in multiple trades at prices ranging from $22.000 to 22.145, 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.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	08/29/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did Castle Biosciences (CSTL) insider Kristen Oelschlager report on Form 4?

The filer reported the sale of 12,677 shares of common stock at a weighted-average price of $22.019 per share, executed in multiple trades.

Was the insider sale part of a trading plan for CSTL?

Yes. The filing states the transactions were made pursuant to a Rule 10b5-1 plan adopted by the reporting person.

How many Castle Biosciences shares does the reporting person own after the sale?

The reporting person beneficially owned 141,116 shares following the reported transaction.

What price range did the CSTL insider trades occur at?

Trades occurred at prices ranging from $22.000 to $22.145; the weighted-average sale price reported is $22.019.

Were any derivative securities or option exercises reported by the insider?

No. The filing shows only non-derivative common stock dispositions and does not report derivative securities or option transactions.