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
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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).
1. Name and Address of Reporting Person *
Ware Olivia C

(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)
04/28/2026
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
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) $ 7.61 04/28/2026   D     36,806   (1) 05/16/2032 Common Stock 36,806 (1) 0 D  
Stock Option (right to buy) $ 37.94 04/28/2026   D     11,459   (1) 06/14/2033 Common Stock 11,459 (1) 0 D  
Stock Option (right to buy) $ 51.3 04/28/2026   D     8,011   (1) 05/28/2034 Common Stock 8,011 (1) 0 D  
Stock Option (right to buy) $ 63.68 04/28/2026   D     9,174   (1) 05/29/2035 Common Stock 9,174 (1) 0 D  
Explanation of Responses:
1. Pursuant to the Agreement and Plan of Merger, dated February 22, 2026, by and among Arcellx, Inc. ("Company"), Gilead Sciences, Inc. ("Parent"), and Ravens Sub, Inc., a wholly owned subsidiary of Parent ("Purchaser"), Purchaser merged with and into Company (the "Merger"), with Company surviving the Merger as a wholly owned subsidiary of Parent. Each outstanding Company stock option ("Company Option"), whether or not vested, and which had a per share exercise price less than $115 per share (the "Closing Amount"), was canceled and converted into the right to receive (i) a lump sum cash payment equal to (x) the excess 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 contractual contingent value right for each share subject to such Company Option immediately prior to the effective time of the Merger.
/s/ Michelle Gilson, as Attorney-in-Fact 04/28/2026
** Signature of Reporting Person Date
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