Castle Biosciences (CSTL) director converts 13,667 RSUs into common shares

Rhea-AI Filing Summary

Castle Biosciences director Miles Harrison exercised Restricted Stock Units into common stock. On May 22, 2026, 13,667 RSUs converted into 13,667 shares of Common Stock at no cash cost, leaving him with 35,631 common shares held directly after the transaction.

Insider Trade Summary

13,667 shares exercised/converted

Mixed 2 txns

Insider Harrison Miles

Role null

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

Holdings After Transaction: Restricted Stock Units — 0 shares (Direct, null); Common Stock — 35,631 shares (Direct, null)

Footnotes (1)

1. Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock. 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 received: 13,667 shares Post-transaction holdings: 35,631 shares +1 more

4 metrics

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

Shares received 13,667 shares Common Stock issued upon RSU conversion at $0.0000 per share

Post-transaction holdings 35,631 shares Common Stock held directly after the reported transaction

RSU remaining balance 0 units Restricted Stock Units balance for this award following conversion

Key Terms

Restricted Stock Unit ("RSU"), Common Stock, Annual Meeting of Stockholders, Exercise or conversion of derivative security

4 terms

Restricted Stock Unit ("RSU") financial

"Each Restricted Stock Unit ("RSU") represents the right to receive one share"

Common Stock financial

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

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

Annual Meeting of Stockholders financial

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

Exercise or conversion of derivative security financial

"transaction_code_description": "Exercise or conversion of derivative security""

Form 4 Insider Transactions: What Each Field Means →

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^*

Harrison Miles

(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)	35,631	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)

FAQ

What insider transaction did CSTL director Miles Harrison report?

Director Miles Harrison reported exercising Restricted Stock Units into Castle Biosciences common stock. On May 22, 2026, 13,667 RSUs converted into 13,667 common shares, increasing his directly held stake without an open-market purchase or sale.

How many Castle Biosciences (CSTL) shares does Miles Harrison hold after this Form 4?

After the RSU conversion, Miles Harrison holds 35,631 shares of Castle Biosciences common stock directly. These shares reflect his position following the exercise of 13,667 Restricted Stock Units reported in the Form 4 filing.

Was the CSTL Form 4 transaction a market buy or sell of shares?

The Form 4 does not show a market buy or sell. It records an M-code transaction, meaning an exercise or conversion of derivative securities, specifically 13,667 Restricted Stock Units converting into 13,667 common shares at a stated price of zero.

What are Restricted Stock Units (RSUs) in the CSTL Form 4 filing?

Each Restricted Stock Unit represents the right to receive one share of Castle Biosciences common stock. In this filing, 13,667 RSUs were converted into an equal number of common shares, consistent with the footnote describing RSU-to-share conversion mechanics.

What vesting terms are noted for the CSTL Restricted Stock Units?

The filing notes that the RSUs vest in full on the earlier of the one-year anniversary of May 22, 2026, or the day immediately before the next Annual Meeting of Stockholders after the grant date, aligning vesting with time-based and corporate meeting milestones.