Arcellx CFO sells 8,384 shares, exercises options

Arcellx, Inc. chief financial officer Michelle Gilson reported multiple transactions in the company’s common stock.

Rhea-AI Filing Summary

Arcellx, Inc. chief financial officer Michelle Gilson reported multiple transactions in the company’s common stock. On February 19, 2026, she executed open-market sales totaling 8,384 shares at weighted average prices between $67.09 and $69.04, with a portion described as a broker-assisted sale to satisfy tax withholding obligations related to vested restricted stock units. On January 3, 2026, she acquired 15,340 shares through an option exercise at $0.00 per share. After these transactions, she directly owned 45,157 shares of Arcellx common stock.

Insider Trade Summary

Net Seller: 8,384 shares

Net Sell 4 txns

Insider Gilson Michelle

Role CHIEF FINANCIAL OFFICER

Sold 8,384 shs ($573K)

Type	Security	Shares	Price	Value
Sale	Common Stock	2,879	$67.7301	$195K
Sale	Common Stock	5,405	$68.5726	$371K
Sale	Common Stock	100	$69.38	$7K
Exercise	Common Stock	15,340	$0.00	$0.00

Holdings After Transaction: Common Stock — 45,157 shares (Direct)

Footnotes (4)

1. F1. 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 3, 2026.
2. F2. Represents a broker-assisted sale to satisfy the Reporting Person's tax withholding obligations in connection with the vesting of restricted stock units.
3. F3. Represents the weighted average share price of an aggregate total of 2,879 shares sold in the price range of $67.09 to $68.08 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. F4. Represents the weighted average share price of an aggregate total of 5,405 shares sold in the price range of $68.17 to $69.04 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.

FAQ

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What insider transactions did Arcellx (ACLX) report for CFO Michelle Gilson?

Arcellx reported that CFO Michelle Gilson exercised options for 15,340 common shares on January 3, 2026, then sold 8,384 shares on February 19, 2026 in open-market transactions. Some sales were broker-assisted to cover tax withholding on vested restricted stock units.

How many Arcellx (ACLX) shares did the CFO sell and at what prices?

On February 19, 2026, the Arcellx CFO sold 8,384 common shares in several open-market trades. Weighted average prices ranged from about $67.09 to $69.04 per share, with reported averages of $67.7301, $68.5726, and $69.3800 for separate sale blocks.

How many Arcellx (ACLX) shares does the CFO hold after these Form 4 transactions?

After completing the disclosed transactions, Arcellx’s CFO directly held 45,157 shares of Arcellx common stock. This figure reflects the net result of her January 3, 2026 option exercise and the February 19, 2026 open-market sales reported in the Form 4 filing.

Were any Arcellx (ACLX) insider sales related to tax withholding on RSUs?

Yes. One block of Arcellx shares sold by the CFO is identified as a broker-assisted sale to satisfy tax withholding obligations. This obligation arose in connection with the vesting of restricted stock units previously reported in an earlier Form 4 filing dated January 3, 2026.

What type of equity award did the Arcellx (ACLX) CFO exercise in January 2026?

The Arcellx CFO exercised a derivative security, acquiring 15,340 common shares on January 3, 2026 at an exercise price of $0.00 per share. Footnotes indicate these relate to restricted stock units, each representing a contingent right to receive one common share.

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Form 4 Insider Transactions: What Each Field Means →

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Accepted by SEC EDGAR 02/19/2026 - 06:26 PM EST Learn about SEC filing dates

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^*

Gilson Michelle

(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 FINANCIAL OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
02/19/2026

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)	01/03/2026		M		15,340	A	$0	44,302	D
Common Stock	02/19/2026		S(2)		2,879	D	$67.7301(3)	50,662	D
Common Stock	02/19/2026		S(2)		5,405	D	$68.5726(4)	45,257	D
Common Stock	02/19/2026		S(2)		100	D	$69.38	45,157	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 3, 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 2,879 shares sold in the price range of $67.09 to $68.08 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. Represents the weighted average share price of an aggregate total of 5,405 shares sold in the price range of $68.17 to $69.04 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	02/19/2026
	** 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).
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