Arcellx (ACLX) director trades 6,000 shares under Rule 10b5-1 plan

Rhea-AI Filing Summary

Arcellx, Inc. director David Charles Lubner reported option exercises and share sales in the company’s stock. On January 20, 2026, he exercised a stock option for 6,000 shares of common stock at an exercise price of $6.28 per share, issued under Arcellx’s 2017 Equity Incentive Plan. On the same day, he sold 6,000 shares of common stock at a price of $75 per share pursuant to a pre-arranged Rule 10b5-1 trading plan that he entered into on September 29, 2025. After these transactions, he directly held 21,659 shares of Arcellx common stock and 59,405 stock options.

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).

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^*

Lubner David Charles

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
01/20/2026

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	01/20/2026		M		6,000	A	$6.28	27,659	D
Common Stock	01/20/2026		S(1)		6,000	D	$75	21,659	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
Stock Option (right to buy)	$6.28	01/20/2026		M			6,000	(2)	06/09/2031	Common Stock	6,000	$0	59,405	D

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 September 29, 2025.

2. Shares issued pursuant to the Issuer's 2017 Equity Incentive Plan (the "2017 Plan"). Subject to the Reporting Person continuing to be a Service Provider (as defined 2017 Plan) through each applicable date, one forty-eighth (1/48th) of the shares subject to the option shall vest each month following the Vesting Commencement Date on the same day of the month as the Vesting Commencement Date (and if there is no corresponding day, on the last day of the month). "Vesting Commencement Date" shall mean June 9, 2021.

	/s/ Michelle Gilson, as Attorney-in-Fact	01/20/2026
	** 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 transaction did Arcellx (ACLX) report for David Charles Lubner?

Arcellx reported that director David Charles Lubner exercised 6,000 stock options and sold 6,000 shares of common stock on January 20, 2026.

At what prices did David Charles Lubner exercise and sell Arcellx (ACLX) shares?

He exercised options for 6,000 shares at an exercise price of $6.28 per share and sold 6,000 shares of Arcellx common stock at $75 per share.

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

Yes. The sale of 6,000 shares was effected under a Rule 10b5-1 trading plan that David Charles Lubner entered into on September 29, 2025.

How many Arcellx (ACLX) shares does David Charles Lubner own after the reported transactions?

Following the transactions, he directly owned 21,659 shares of Arcellx common stock and held 59,405 stock options.

What is David Charles Lubner’s relationship to Arcellx (ACLX)?

David Charles Lubner is reported as a director of Arcellx, Inc. and is not listed as an officer or 10% owner in this filing.

Under which equity plan were the exercised Arcellx (ACLX) stock options granted?

The 6,000 stock options exercised on January 20, 2026 were issued under Arcellx’s 2017 Equity Incentive Plan, with vesting beginning on June 9, 2021.