CSTL director converts RSUs into 13,667 shares

CASTLE BIOSCIENCES INC director Rodney Cotton acquired shares through an equity award conversion.

Rhea-AI Filing Summary

CASTLE BIOSCIENCES INC director Rodney Cotton acquired shares through an equity award conversion. On May 22, 2026, he exercised Restricted Stock Units into 13,667 shares of Common Stock at a stated price of $0.00 per share.

Following this transaction, Cotton directly owned 32,998 shares of Common Stock. A corresponding derivative entry shows the 13,667 Restricted Stock Units converted into the same number of Common shares, leaving no RSUs from this grant outstanding.

Insider Trade Summary

13,667 shares exercised/converted

Exercise 2 txns

Insider Cotton Rodney

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 — 32,998 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 via RSU conversion: 13,667 shares Post-transaction holdings: 32,998 shares +1 more

4 metrics

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

Shares acquired via RSU conversion 13,667 shares Common Stock received from RSU exercise on May 22, 2026

Post-transaction holdings 32,998 shares Common Stock directly owned by Rodney Cotton after transaction

RSU to share ratio 1 RSU : 1 share Each RSU represents the right to receive one Common share

Key Terms

Restricted Stock Units, Common Stock, Exercise or conversion of derivative security, Annual Meeting of Stockholders

4 terms

Restricted Stock Units financial

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

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.

Common Stock financial

"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.

Exercise or conversion of derivative security financial

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

Annual Meeting of Stockholders financial

"the day immediately preceding the next Annual Meeting of Stockholders"

FAQ

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

What did CSTL director Rodney Cotton report in this Form 4?

Rodney Cotton reported an equity award conversion, exercising Restricted Stock Units into 13,667 shares of Castle Biosciences Common Stock. This increased his directly held Common Stock position while eliminating the corresponding RSU derivative position from this particular grant.

How many Castle Biosciences (CSTL) shares did Rodney Cotton acquire?

Rodney Cotton acquired 13,667 shares of Common Stock through the exercise of Restricted Stock Units. The Form 4 shows this as a derivative exercise transaction, moving value from RSUs into directly held Common shares rather than an open-market purchase.

What is Rodney Cotton’s Castle Biosciences share ownership after this transaction?

After the RSU exercise, Rodney Cotton directly owned 32,998 shares of Castle Biosciences Common Stock. This total reflects his updated direct holdings following the conversion of 13,667 Restricted Stock Units into the same number of Common shares.

Was Rodney Cotton’s CSTL transaction a market purchase or sale?

The transaction was not a market purchase or sale. It is coded "M" on the Form 4, indicating an exercise or conversion of derivative securities, specifically Restricted Stock Units, into Common Stock at a stated price of $0.00 per share.

What do the Restricted Stock Units in this CSTL Form 4 represent?

Each Restricted Stock Unit represents the right to receive one share of Castle Biosciences Common Stock. In this filing, 13,667 RSUs were exercised and converted into 13,667 Common shares, and the RSU balance from this grant was reduced to zero.

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^*

Cotton Rodney

(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)	32,998	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)