ACLX insider sale: 12,396 shares sold via 10b5-1 plan at ~$80.12

Rhea-AI Filing Summary

Arcellx insider sale under 10b5-1 plan. The chief medical officer sold 12,396 shares of Arcellx common stock under a Rule 10b5-1 trading plan, at a weighted average price of $80.119 per share, and now beneficially owns 21,731 shares. The filing reports the transaction as a sale and identifies the sale price range as $80.00 to $80.41 with the weighted average disclosed. The reporting person indicates the sale was pre-arranged under a March 23, 2025 10b5-1 plan and offers to provide breakdown by price on request.

Positive

• Sale executed under a Rule 10b5-1 trading plan, indicating a pre-established, non-discretionary disposition framework
• Weighted average sale price disclosed ($80.119) and a price range ($80.00 to $80.41), providing pricing transparency
• Reporting person offers to provide detailed price-by-price breakdown on request, supporting transparency

Negative

• Beneficial ownership decreased by the reported sale, leaving the reporting person with 21,731 shares
• No information provided on dollar value retained or percentage ownership relative to outstanding shares, limiting context for investors

Insights

Securities Analyst

TL;DR: Insider sold a portion of holdings via a 10b5-1 plan; remaining ownership is disclosed at 21,731 shares.

The transaction is an organized sale under a Rule 10b5-1 trading plan, which generally indicates pre-planned dispositions rather than opportunistic sales based on inside information. The sale size—12,396 shares at a weighted average of $80.119—reduced the reporting person's beneficial ownership to 21,731 shares. From a disclosure perspective, the filing is clean: it specifies the 10b5-1 plan date and provides the weighted average price and price range. No derivative transactions or other changes in ownership form are reported.

Corporate Governance Expert

TL;DR: Governance disclosure follows standard practice; sale executed under an established trading plan with pricing transparency.

The Form 4 clearly states the sale was effected pursuant to a 10b5-1 trading plan entered on March 23, 2025, and discloses the aggregate shares sold and weighted average price. This provides reasonable governance transparency about the insider's liquidity event. The filer also commits to supplying itemized share-price sale details on request, which supports regulatory compliance and stakeholder transparency. No related-party transfers or indirect ownership changes are disclosed.

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).

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)
09/26/2025

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	09/26/2025		S(1)		12,396	D	$80.119(2)	21,731	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.

2. Represents the weighted average share price of an aggregate total of 12,396 shares sold in the price range of $80.00 to $80.41 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.

	Michelle Gilson	09/26/2025
	** 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 did Arcellx insider sell in the Form 4 (ACLX)?

The chief medical officer sold 12,396 shares of common stock pursuant to a Rule 10b5-1 trading plan.

At what price were the ACLX shares sold?

Weighted average price was $80.119 per share; the disclosed price range was $80.00 to $80.41.

How many ACLX shares does the reporting person own after the sale?

The reporting person beneficially owns 21,731 shares following the reported transaction.

Was this sale part of a pre-arranged plan?

Yes; the sale was effected under a Rule 10b5-1 trading plan entered into on March 23, 2025.

Does the Form 4 report any option exercises or derivative transactions?

No derivative securities or option exercises are reported on this Form 4.