Castle Biosciences director exercises 13,667 RSUs

Castle Biosciences director Kim Caple exercised equity awards into common stock.

Rhea-AI Filing Summary

Castle Biosciences director Kim Caple exercised equity awards into common stock. On May 22, 2026, Caple converted 13,667 Restricted Stock Units into 13,667 shares of Common Stock at a price of $0.00 per share, classified as a derivative exercise rather than a market purchase.

Following this transaction, Caple directly holds 36,121 shares of Common Stock. The filing shows no open-market sales or gifts, indicating a routine compensation-related equity settlement rather than a discretionary trade. Each RSU represented the right to receive one share of Common Stock.

Insider Trade Summary

13,667 shares exercised/converted

Exercise 2 txns

Insider Caple Kim

Role Director

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	13,667	$0.00	$0.00
Exercise	Common Stock	13,667	$0.00	$0.00

Holdings After Transaction: Restricted Stock Units — 0 contracts (Direct); Common Stock — 36,121 shares (Direct)

Footnotes (2)

1. F1. Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.
2. F2. The RSUs vest in full on the earlier of the (a) one-year anniversary of the date on May 22, 2026, or (b) the day immediately preceding the next Annual Meeting of Stockholders following the date of the grant.

Key Figures

RSUs exercised: 13,667 units Shares acquired from exercise: 13,667 shares Post-transaction holdings: 36,121 shares +2 more

5 metrics

RSUs exercised 13,667 units Restricted Stock Units converted to Common Stock on May 22, 2026

Shares acquired from exercise 13,667 shares Common Stock received from RSU exercise at $0.00 per share

Post-transaction holdings 36,121 shares Total Common Stock directly held by Kim Caple after transactions

Exercise price per share $0.00/share Price listed for derivative RSU conversion into Common Stock

Derivative exercises 1 transaction, 13,667 shares transactionSummary exerciseCount and exerciseShares

Key Terms

Restricted Stock Units, derivative security, Annual Meeting of Stockholders

3 terms

Restricted Stock Units financial

"Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

derivative security financial

"transaction_code_description: Exercise or conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

Annual Meeting of Stockholders financial

"the day immediately preceding the next Annual Meeting of Stockholders following the date of the grant."

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Kim Caple report for CASTLE BIOSCIENCES (CSTL)?

Kim Caple reported exercising 13,667 Restricted Stock Units into 13,667 shares of Common Stock. This was a derivative exercise at $0.00 per share, reflecting settlement of equity compensation rather than an open-market stock purchase or sale.

How many CASTLE BIOSCIENCES (CSTL) shares does Kim Caple hold after this Form 4?

After the reported transactions, Kim Caple directly holds 36,121 shares of CASTLE BIOSCIENCES Common Stock. This total reflects the addition of 13,667 shares received from exercising Restricted Stock Units on May 22, 2026.

Did Kim Caple buy or sell CASTLE BIOSCIENCES (CSTL) shares on the market?

The filing shows no open-market buys or sells. Instead, Kim Caple exercised 13,667 Restricted Stock Units into 13,667 shares of Common Stock, a compensation-related derivative exercise coded as “M,” not a market trade.

What does the 13,667-share RSU exercise mean for CSTL insider activity?

The 13,667-share RSU exercise represents conversion of previously granted equity awards into Common Stock. It is categorized as a derivative exercise, indicating routine compensation vesting rather than a new investment decision or liquidation of existing holdings.

How are Kim Caple’s Restricted Stock Units in CASTLE BIOSCIENCES structured?

Each Restricted Stock Unit represents the right to receive one share of CASTLE BIOSCIENCES Common Stock. The filing notes RSUs vest in full based on a time-based schedule linked to the one-year anniversary of May 22, 2026 or the next Annual Meeting.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/27/2026 - 04:16 PM EDT Learn about SEC filing dates

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^*

Caple Kim

(Last) (First) (Middle)

C/O CASTLE BIOSCIENCES, INC.

1500 W. PARKWOOD AVE SUITE 400

(Street)

FRIENDSWOOD TEXAS 77546

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/22/2026

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

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

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

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	05/22/2026		M		13,667	A	(1)	36,121	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
Restricted Stock Units	(1)	05/22/2026		M			13,667	(2)	(2)	Common Stock	13,667	$0	0	D

Explanation of Responses:

1. Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.

2. The RSUs vest in full on the earlier of the (a) one-year anniversary of the date on May 22, 2026, or (b) the day immediately preceding the next Annual Meeting of Stockholders following the date of the grant.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	05/27/2025
	** 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.
* Form 4: SEC 1474 (03-26)