Tax-withholding sale by Arcellx (NASDAQ: ACLX) director Elghandour

Rhea-AI Filing Summary

Arcellx, Inc. director and officer Rami Elghandour reported multiple stock transactions. On February 27, 2026, he completed an open-market, broker-assisted sale of 89,916 shares of common stock at a weighted average price of $113.9204 per share to cover tax withholding obligations from previously vested restricted stock units.

Following this sale, he held 276,051 shares directly. Earlier in January 2026, he acquired 55,991, 53,098 and 55,459 shares of common stock through exercises or conversions of derivative securities at $0.0000 per share. In addition, 198,000 shares and 218,500 shares are held indirectly in spousal lifetime access non-grantor trusts, where he may be deemed to have beneficial ownership but disclaims ownership except for any pecuniary interest.

Insights

Equity analyst

Filing shows tax-related share sale offset by prior option exercises.

Arcellx director and officer Rami Elghandour reported an open-market sale of 89,916 common shares at a weighted average price of $113.9204 per share. A footnote explains this was a broker-assisted sale to satisfy tax withholding tied to vested restricted stock units, not a discretionary cash-raising sale.

The filing also lists three earlier transactions in January 2026, where he acquired 55,991, 53,098 and 55,459 common shares at $0.0000 per share through exercises or conversions of derivative securities. Combined with indirect holdings in two spousal lifetime access non-grantor trusts, this indicates continued substantial exposure to Arcellx equity despite the tax-driven sale.

Overall, this appears to be routine insider activity associated with equity compensation vesting rather than a signal of a change in outlook. Subsequent company filings may provide further context on future equity compensation or additional insider transactions.

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

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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^*

Elghandour Rami

(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
X	Officer (give title below)		Other (specify below)
	SEE REMARKS

3. Date of Earliest Transaction (Month/Day/Year)
02/27/2026

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		55,459	A	$0	673,378	D
Common Stock(1)	01/03/2026		M		53,098	A	$0	726,476	D
Common Stock(1)	01/06/2026		M		55,991	A	$0	782,467	D
Common Stock	02/27/2026		S(2)		89,916	D	$113.9204(3)	276,051	D
Common Stock								198,000	I(4)	By Trust
Common Stock								218,500	I(5)	By Trust

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 89,916 shares sold in the price range of $113.83 to $114.25 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.

4. Shares held by a spousal lifetime access non-grantor trust, of which the Reporting Person's spouse is the beneficiary and for which the Reporting Person may be deemed to have Section 16 beneficial ownership. The Reporting Person disclaims beneficial ownership except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of such shares for Section 16 or any other purpose.

5. Shares held by a spousal lifetime access non-grantor trust of which the Reporting Person is a beneficiary and for which the Reporting Person may be deemed to have Section 16 beneficial ownership. The Reporting Person disclaims beneficial ownership except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of such shares for Section 16 or any other purpose.

Remarks:

President, CEO and Chairman of the Board

	/s/ Michelle Gilson, as Attorney-in-Fact	02/27/2026
	** 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.
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FAQ

What insider transactions did Arcellx (ACLX) report for Rami Elghandour?

Arcellx reported that director and officer Rami Elghandour sold 89,916 common shares and exercised derivative securities for 55,991, 53,098 and 55,459 shares. These transactions reflect tax-withholding sales and equity award exercises rather than a simple open-market portfolio adjustment.

At what price did Rami Elghandour sell Arcellx (ACLX) shares?

He sold 89,916 shares of Arcellx common stock at a weighted average price of $113.9204 per share. A footnote states the sale price range was $113.83 to $114.25, and details by price level are available upon request from the issuer or regulators.

Why did Rami Elghandour sell 89,916 Arcellx (ACLX) shares?

The filing states the 89,916-share sale was a broker-assisted transaction to satisfy tax withholding obligations from vesting restricted stock units. This means the sale was conducted to cover tax liabilities triggered by equity compensation vesting rather than a discretionary sale for liquidity.

How many Arcellx (ACLX) shares does Rami Elghandour hold after these transactions?

After the reported sale, he directly owned 276,051 Arcellx common shares. The filing also shows indirect holdings of 198,000 and 218,500 shares in separate spousal lifetime access non-grantor trusts, where he may be deemed a beneficial owner but disclaims ownership beyond any pecuniary interest.

What were the Arcellx (ACLX) derivative exercises reported by Rami Elghandour?

The filing shows three derivative exercise or conversion transactions for 55,991, 53,098 and 55,459 common shares, each at a price of $0.0000 per share. These represent the conversion of previously granted derivative securities into common stock as part of his equity compensation.

How are the Arcellx (ACLX) trust-held shares related to Rami Elghandour?

Two blocks of 198,000 and 218,500 Arcellx shares are held by spousal lifetime access non-grantor trusts. Footnotes state he may be deemed to have Section 16 beneficial ownership but disclaims beneficial ownership except for any pecuniary interest, clarifying the indirect nature of these holdings.