Michelle Gilson - 28 Apr 2026 Form 4 Insider Report for Arcellx, Inc. (ACLX)

Reporting relationship: CHIEF FINANCIAL OFFICER
Issuer ticker: ACLX
Reported as of: 28 Apr 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 28 Apr 2026, 16:25:47 UTC
Prior SEC filing: 17 Apr 2026
Source filing: View source filing
Reporting owner signature: /s/ Michelle Gilson

Key filing fact

Michelle Gilson filed Form 4 for Arcellx, Inc. (ACLX) on 28 Apr 2026.

Key facts

This page summarizes Michelle Gilson's Form 4 filing for Arcellx, Inc. (ACLX).
11 reported transactions and 9 derivative rows are listed below.
Accepted by SEC: 28 Apr 2026, 16:25.

Change

Previous filing in this sequence was filed on 17 Apr 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001930862 Primary reporting owner

Gilson Michelle

Relationship: CHIEF FINANCIAL OFFICER
Address: C/O ARCELLX, INC., 800 BRIDGE PARKWAY, REDWOOD CITY
Signature: /s/ Michelle Gilson
Signature date: 28 Apr 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

ACLX transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -67,048
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Footnotes: F1

ACLX transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -5,000
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: By foundation
Footnotes: F1, F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

ACLX transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -40,205
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 40,205
Exercise price: $8.66
Footnotes: F3

ACLX transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -32,500
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 32,500
Exercise price: $19.97
Footnotes: F3

ACLX transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -70,796
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 70,796
Exercise price: $31.03
Footnotes: F3

ACLX transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -94,596
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 94,596
Exercise price: $56.15
Footnotes: F3

ACLX transaction Derivative

Restricted Stock Unit

Disposed to Issuer

Transaction value
Shares: -20,496
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 20,496
Exercise price
Footnotes: F4, F5

ACLX transaction Derivative

Restricted Stock Unit

Disposed to Issuer

Transaction value
Shares: -61,590
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 61,590
Exercise price
Footnotes: F4, F5

ACLX transaction Derivative

Restricted Stock Unit

Disposed to Issuer

Transaction value
Shares: -88,542
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 88,542
Exercise price
Footnotes: F4, F5

ACLX transaction Derivative

Performance-based Restricted Stock Unit

Award

Transaction value
Shares: +59,028
Change %
Price
Shares after: 59,028
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 59,028
Exercise price
Footnotes: F4, F5

ACLX transaction Derivative

Performance-based Restricted Stock Unit

Disposed to Issuer

Transaction value
Shares: -59,028
Change %: -100%
Price
Shares after: 0
Date: 28 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 59,028
Exercise price
Footnotes: F4, F5

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Michelle Gilson is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 5 footnotes

Footnote F1

Pursuant to the Agreement and Plan of Merger, dated February 22, 2026 (the "Merger Agreement"), by and among Arcellx, Inc. ("Company"), Gilead Sciences, Inc. ("Parent"), and Ravens Sub, Inc., a wholly owned subsidiary of Parent ("Purchaser"), the shares of common stock of Company that were tendered to Purchaser prior to the expiration time of the offer were exchanged for (x) $115.00 per share ("Closing Amount"), net to the seller in cash, without interest, subject to withholding tax, plus (y) one contractual contingent value right (a "CVR"), which represents the right to receive one contingent payment of $5.00 per CVR in cash, without interest, and subject to any withholding tax, pursuant to the terms and subject to the conditions of a contingent value rights agreement. After completion of the tender offer, pursuant to the terms of the Merger Agreement, Purchaser merged with and into Company (the "Merger"), with Company surviving the Merger as a wholly owned subsidiary of Parent.

Footnote F2

Shares held by a a family charitable foundation, of which the Reporting Person serves as the President. The Reporting Person has voting and investment power over all securities owned by the foundation.

Footnote F3

Pursuant to the Merger Agreement, each outstanding option to purchase shares of Common Stock (a "Company Option"), whether or not vested, and which had a per share exercise price that was less than the Closing Amount, was canceled and converted into the right of the holder to receive (i) (subject to any applicable withholding taxes) a lump-sum cash payment equal to (x) the excess (if any) of (a) the Closing Amount over (b) the per share exercise price subject to such Company Option, multiplied by (y) the total number of shares subject to such Company Option immediately prior to the effective time of the Merger, and (ii) one (1) CVR for each share subject to such Company Option immediately prior to the effective time of the Merger.

Footnote F4

Each restricted stock unit represents a contingent right to receive one share of Company Common Stock.

Footnote F5

Pursuant to the Merger Agreement, each outstanding restricted stock unit (a "Company RSU"), whether or not vested, was canceled and converted into the right of the holder to receive (i) (subject to any applicable withholding taxes) a lump-sum cash payment equal to (x) the Closing Amount, multiplied by (y) the total number of shares subject to such Company RSU immediately prior to the effective time of the Merger (with the number of shares underlying any Company RSUs that were subject to performance-based vesting conditions determined based on achievement of actual performance in connection with the Merger, as determined by the Company's board of directors or a committee thereof), and (ii) one (1) CVR for each share subject to such Company RSU immediately prior to the effective time of the Merger.