Arcellx (ACLX) CMO details RSU vesting and tax share sale in Form 4

Rhea-AI Filing Summary

Arcellx, Inc.’s Chief Medical Officer Christopher Heery reported RSU vesting and a related share sale. On 01/03/2026 he acquired 16,520 shares of Common Stock at an exercise price of $0, reflecting settlement of previously granted restricted stock units, each representing one share.

On 01/13/2026 he sold 7,437 shares of Common Stock at a weighted average price of $65.512 per share in a broker-assisted transaction to satisfy tax withholding obligations tied to the RSU vesting. After these transactions, he directly beneficially owns 29,631 shares of Arcellx Common Stock.

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

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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^*

Heery Christopher

(Last) (First) (Middle)

C/O ARCELLX, INC.

800 BRIDGE PARKWAY

(Street)

REDWOOD CITY CA 94065

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Arcellx, Inc. [ ACLX ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
01/13/2026

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(1)	01/03/2026		M		16,520	A	$0	30,135	D
Common Stock	01/13/2026		S(2)		7,437	D	$65.512(3)	29,631	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

Explanation of Responses:

1. Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock. Vesting of these RSUs previously reported in the Form 4 filed January 6, 2026.

2. Represents a broker-assisted sale to satisfy the Reporting Person's tax withholding obligations in connection with the vesting of restricted stock units.

3. The price reported reflects the weighted average sales price. These shares were sold in multiple transactions at prices that were not available from the broker at the time of filing. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price.

	/s/ Michelle Gilson, as Attorney-in-Fact	01/13/2026
	** 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).
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FAQ

Who is the insider reporting this Form 4 for Arcellx (ACLX)?

The reporting person is Christopher Heery, who serves as Chief Medical Officer of Arcellx, Inc. and filed individually as one reporting person.

What shares did Arcellx (ACLX) CMO Christopher Heery acquire in this filing?

On 01/03/2026, he acquired 16,520 shares of Arcellx Common Stock at an exercise price of $0, corresponding to the vesting and settlement of previously granted restricted stock units.

How many Arcellx (ACLX) shares did the CMO sell and at what price?

On 01/13/2026, he sold 7,437 shares of Arcellx Common Stock at a weighted average price of $65.512 per share in a broker-assisted transaction.

Why were the Arcellx (ACLX) shares sold in this Form 4?

The 7,437-share sale represents a broker-assisted sale to satisfy tax withholding obligations related to the vesting of restricted stock units.

How many Arcellx (ACLX) shares does the CMO own after these transactions?

Following the reported transactions, Christopher Heery directly beneficially owns 29,631 shares of Arcellx Common Stock.

What does the weighted average price disclosure mean in this Arcellx (ACLX) Form 4?

The sale price of $65.512 per share is a weighted average across multiple trade prices. The reporting person undertakes to provide full trade-by-trade pricing details to the SEC staff, the issuer, or any security holder upon request.