Arcellx, Inc. — Director's Dealing 2023

May 16, 2023

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Arcellx, Inc. (ACLX)
CIK: 0001786205
Period of Report: 2023-05-11

Reporting Person: SR ONE CAPITAL MANAGEMENT, LLC (10% Owner)
Reporting Person: SR One Capital Fund I Aggregator LP (10% Owner)
Reporting Person: SR ONE CAPITAL PARTNERS I, LP (10% Owner)
Reporting Person: George Simeon (10% Owner)
Reporting Person: SR One Co-Invest II, LLC (10% Owner)
Reporting Person: SR One Co-Invest II Manager, LLC (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2023-05-11	Common Stock	S	631932	$45.00	Disposed	2834879	Indirect
2023-05-11	Common Stock	S	370612	$45.00	Disposed	1662584	Indirect
2023-05-11	Common Stock	S	6485	$46.15	Disposed	2828394	Indirect
2023-05-11	Common Stock	S	3804	$46.15	Disposed	1658780	Indirect

Footnotes

F1: The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $45.00 to $45.745 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission (the "SEC"), upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

F2: The securities are directly held by SR One Capital Fund I Aggregator, LP ("SR One Fund I Aggregator"). SR One Capital Partners I, LP ("SR One Partners I") is the sole general partner of SR One Fund I Aggregator, and SR One Capital Management, LLC ("SR One Capital Management") is the sole general partner of SR One Partners I. Simeon George, M.D. is the managing member of SR One Capital Management (SR One Partners I, SR One Capital Management, and Dr. George together, the "Fund I Indirect Reporting Persons"). The Fund I Indirect Reporting Persons disclaim beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended ("Section 16"), or otherwise of such portion of the securities held by SR One Fund I Aggregator in which the Fund I Indirect Reporting Persons have no pecuniary interest.

F3: The securities are directly held by SR One Co-Invest II, LLC ("SR One Co-Invest II"). SR One Co-Invest II Manager, LLC ("SR One Co-Invest II Manager") is the managing member of SR One Co-Invest II and SR One Capital Management is the managing member of SR One Co-Invest II Manager. Dr. George is the managing member of SR One Capital Management (SR One Co-Invest II Manager, SR One Capital Management, and Dr. George together, the "Co-Invest II Indirect Reporting Persons"). The Co-Invest II Indirect Reporting Persons disclaim beneficial ownership within the meaning of Section 16 or otherwise of such portion of the securities held by SR One Co-Invest II in which the Co-Invest II Indirect Reporting Persons have no pecuniary interest.

F4: The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $46.00 to $46.56 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.