[Form 4] Arcellx, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Arcellx, Inc. reported an insider stock transaction by its chief medical officer on a Form 4. On November 17, 2025, the officer sold 340 shares of common stock at $90 per share, leaving 284 shares beneficially owned directly after the sale. The filing notes that this sale was carried out under a pre-arranged Rule 10b5-1 trading plan that the reporting person entered into on March 23, 2025, which is designed to allow insiders to sell stock according to a preset schedule.

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
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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).

X

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)
11/17/2025

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	11/17/2025		S(1)		340	D	$90	284	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. The sale of shares reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan entered into by the Reporting Person on March 23, 2025.

	/s/ Michelle Gilson, as Attorney-in-Fact	11/17/2025
	** 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.

FAQ

What insider transaction did Arcellx (ACLX) report in this Form 4?

The filing reports that the chief medical officer of Arcellx, Inc. sold 340 shares of common stock on November 17, 2025 at a price of $90 per share.

How many Arcellx (ACLX) shares does the insider hold after the reported sale?

Following the reported transaction, the officer beneficially owns 284 shares of Arcellx common stock, held directly.

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

The reporting person is an officer of Arcellx, serving as the company’s chief medical officer.

Was the Arcellx (ACLX) insider sale made under a Rule 10b5-1 plan?

Yes. The sale was effected pursuant to a Rule 10b5-1 trading plan that the reporting person entered into on March 23, 2025.

What is the significance of Rule 10b5-1 in the Arcellx (ACLX) Form 4?

The filing states that the transaction was made under a Rule 10b5-1 trading plan, which is intended to satisfy the rule’s affirmative defense conditions for pre-scheduled insider trades.

Is this Arcellx (ACLX) Form 4 filed for one or multiple reporting persons?

The Form 4 is indicated as being filed by one reporting person.