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

Rhea-AI Filing Summary

Kristen M. Oelschlager, Chief Operating Officer and Director of Castle Biosciences, Inc. (CSTL), reported transactions on 08/08/2025 on a Form 4. The filing shows an acquisition of 10,640 shares of common stock at a reported price of $0, and a disposition of 2,804 shares at $19.36 per share. The filing records 171,800 shares beneficially owned following the reported transactions. Table II and the explanation state these 10,640 units relate to Performance-Based Stock Units (PSUs), each representing one share; the PSUs comprised the remaining 50% of a grant made on December 23, 2022, which vested on August 9, 2024.

Positive

• 10,640 shares acquired via Performance-Based Stock Units, explicitly disclosed in the filing
• PSUs clarified as the remaining 50% of the 12/23/2022 grant and noted as vested on 08/09/2024

Negative

• 2,804 shares disposed at a price of $19.36 on 08/08/2025
• Final direct beneficial ownership reduced to 171,800 shares after the reported transactions

Insights

Securities Analyst

TL;DR: Insider received 10,640 shares via PSUs and sold 2,804 shares; overall insider holdings remain substantial at 171,800 shares.

The Form 4 documents a routine equity event: conversion/receipt of 10,640 shares tied to performance-based stock units and a contemporaneous sale of 2,804 shares at $19.36. The PSU explanation is explicit: these units were the remaining 50% of a 12/23/2022 grant and had vested on 8/9/2024, indicating the acquisition is the mechanical result of vesting rather than a negotiated purchase. The filing leaves total direct beneficial ownership at 171,800 shares, which is relevant for dilution and insider alignment analysis but does not by itself indicate a change in company fundamentals.

Corporate Governance Expert

TL;DR: Transaction appears administrative—vested PSUs converted to shares with a smaller sale; governance signals are neutral.

The narrative in the filing clarifies these are Performance-Based Stock Units representing one share each and that they comprised the remaining 50% of a prior grant that vested on 8/9/2024. Such disclosures are consistent with standard executive compensation settlement and required reporting. The concurrent disposal of 2,804 shares at $19.36 is documented. From a governance perspective, the filing provides clear traceability of grant, vesting, and disposition dates and quantities, with no additional conditions or arrangements disclosed.

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).

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)
08/08/2025

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	08/08/2025		M		10,640	A	$0	174,604	D
Common Stock	08/08/2025		F		2,804	D	$19.36	171,800	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
Performance-Based Stock Unit	(1)	08/08/2025		M			10,640	(1)	(1)	Common Stock	10,640	$0	0	D

Explanation of Responses:

1. Each Performance-Based Stock Unit ("PSU") represents the right to receive one share of the Issuer's Common Stock. These PSUs represent the remaining 50% of the PSUs granted on December 23, 2022, which were all subject to time-based vesting and vested in full on the one-year anniversary of August 9, 2024.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	08/12/2025
	** 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 Kristen Oelschlager report on the Form 4 for CSTL?

The Form 4 reports an acquisition of 10,640 shares tied to Performance-Based Stock Units and a disposition of 2,804 shares at $19.36 on 08/08/2025.

How many shares does Kristen Oelschlager beneficially own after the transactions?

The filing shows 171,800 shares beneficially owned following the reported transactions.

What are the Performance-Based Stock Units mentioned in the CSTL Form 4?

Each PSU represents the right to receive one share of common stock; these PSUs were the remaining 50% of a grant from 12/23/2022 and vested on 08/09/2024.

What price was reported for the shares sold by the insider?

The filing reports a disposition of 2,804 shares at a price of $19.36 per share.

What is the reporting person's role at Castle Biosciences (CSTL)?

The reporting person is Kristen M. Oelschlager, listed as Chief Operating Officer and a Director of the issuer.