Sec Form 4 Filing - NEA Partners 15, L.P. @ Arcellx, Inc. - 2022-12-20

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person NEA Partners 15, L.P. 2. Issuer Name and Ticker or Trading Symbol Arcellx, Inc. [ ACLX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1954 GREENSPRING DRIVE, SUITE 600 3. Date of Earliest Transaction (MM/DD/YY) 12/20/2022 (Street) TIMONIUM, MD21093 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 12/20/2022 J( 1 ) 2,000,000 D $ 0 4,745,262 I See Note 2( 2 ) Common Stock 12/20/2022 J( 3 ) 30,000 A $ 0 30,000 D( 4 ) Common Stock 12/20/2022 J( 5 ) 30,000 D $ 0 0 D( 4 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other NEA Partners 15, L.P. 1954 GREENSPRING DRIVE SUITE 600 TIMONIUM, MD21093 X NEA 15 GP, LLC 1954 GREENSPRING DRIVE SUITE 600 TIMONIUM, MD21093 X Signatures /s/ Louis Citron, attorney-in-fact 12/22/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )New Enterprise Associates 15, L.P. ("NEA 15") made a pro rata distribution of 2,000,000 shares of Common Stock of the Issuer to its general partner and limited partners for no consideration on December 20, 2022. ( 2 )The securities are directly held by NEA 15 and are indirectly held by NEA Partners 15, L.P. ("NEA Partners 15"), the sole general partner of NEA 15, NEA 15 GP, LLC ("NEA 15 GP"), the sole general partner of NEA Partners 15, and the individual managers of NEA 15 GP (NEA Partners 15, NEA 15 GP and the individual managers of NEA 15 GP (collectively, the "NEA 15 Managers"), together, the "NEA 15 Indirect Reporting Persons"). The NEA 15 Managers are Forest Baskett, Anthony A. Florence, Jr., Mohamad Makhzoumi, Scott D. Sandell and Peter W. Sonsini. The NEA 15 Indirect Reporting Persons disclaim beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 15 in which the NEA 15 Indirect Reporting Persons have no pecuniary interest. ( 3 )NEA Partners 15 received 30,000 shares of Common Stock of the Issuer in the distribution made by NEA 15 on December 20, 2022. ( 4 )The securities are directly held by NEA Partners 15 and indirectly held by NEA 15 GP, the sole general partner of NEA Partners 15, and the NEA 15 Managers (NEA 15 GP and the NEA 15 Managers together, the "NEA Partners 15 Indirect Reporting Persons"). The NEA Partners 15 Indirect Reporting Persons disclaim beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA Partners 15 in which the NEA Partners 15 Indirect Reporting Persons have no pecuniary interest. ( 5 )NEA Partners 15 made a pro rata distribution of 30,000 shares of Common Stock of the Issuer to its limited partners for no consideration on December 20, 2022.

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).

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