Arcellx (ACLX) CMO logs option exercise and tax-related share sale

Rhea-AI Filing Summary

Arcellx, Inc. chief medical officer Christopher Heery reported two equity transactions in company stock. On 01/02/2026, he exercised options coded "M" for 13,021 shares of common stock at a price of $0 per share, increasing his directly held position to 13,615 shares.

On 01/12/2026, he executed a broker-assisted sale coded "S" of 6,131 common shares at a weighted average price of $64.1471 per share to cover tax withholding obligations tied to restricted stock unit vesting. Following these transactions, he directly owned 37,068 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

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^*

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)
01/12/2026

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)	01/02/2026		M		13,021	A	$0	13,615	D
Common Stock	01/12/2026		S(2)		6,131	D	$64.1471(3)	37,068	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. Represents the weighted average share price of an aggregate total of 6,131 shares sold in the price range of $64.14112 to $64.4463 by the Reporting Person. The Reporting Person undertakes to provide upon request by the Commission staff, the issuer or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

	/s/ Michelle Gilson, as Attorney-in-Fact	01/12/2026
	** 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).
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 insider activity did Arcellx (ACLX) report in this Form 4?

The filing shows that Christopher Heery, Arcellx's chief medical officer, exercised options for 13,021 shares of common stock and later sold 6,131 shares of common stock in a broker-assisted transaction.

Who is the reporting person in the Arcellx (ACLX) Form 4 filing?

The reporting person is Christopher Heery, who serves as chief medical officer of Arcellx, Inc. and filed individually as one reporting person.

How many Arcellx shares did the CMO sell, and at what price?

On 01/12/2026, he sold 6,131 shares of Arcellx common stock at a weighted average price of $64.1471 per share, within a disclosed price range.

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

The sale of 6,131 shares was described as a broker-assisted sale to satisfy the reporting person's tax withholding obligations related to the vesting of restricted stock units.

What option or RSU activity is disclosed for Arcellx's CMO?

The filing notes that each restricted stock unit (RSU) represents a contingent right to receive one share of common stock, and that vesting of these RSUs was previously reported in a Form 4 filed on January 6, 2026.

How many Arcellx shares does the CMO own after the reported transactions?

After the reported exercise and sale transactions, Christopher Heery directly owned 37,068 shares of Arcellx common stock.

Were the Arcellx (ACLX) insider transactions direct or indirect holdings?

Both reported transactions in Arcellx common stock are listed as direct (D) ownership, with no separate entity indicated for indirect beneficial ownership.