X0508 4 2024-01-02 0 0001786205 Arcellx, Inc. ACLX 0001930862 Gilson Michelle C/O ARCELLX, INC. 25 WEST WATKINS MILL ROAD, SUITE A GAITHERSBURG MD 20878 0 1 0 0 Chief Financial Officer 0 Common Stock 2023-01-03 4 M 0 15339 0.00 A 24824 D Stock Option (right to buy) 56.15 2024-01-02 4 A 0 94596 0.00 A 2034-01-02 Common Stock 94596 94596 D Restricted Stock Unit 2024-01-02 4 A 0 61487 0.00 A Common Stock 61487 61487 D Restricted Stock Unit 2024-01-03 4 M 0 15339 0.00 D Common Stock 15339 30679 D Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock. Subject to the Reporting Person continuing to be a Service Provider (as defined in the Issuer's 2022 Equity Incentive Plan) through each applicable vesting date, one forty-eighth (1/48th) of the shares subject to the option will vest each month following the Vesting Commencement Date on the same day of the month as the Vesting Commencement Date (or, if there is no corresponding day in a particular month, then the last day of the month) over four (4) years. "Vesting Commencement Date" shall mean January 1, 2024. Subject to the Reporting Person continuing to be a Service Provider (as defined in the Issuer's 2022 Equity Incentive Plan) through each applicable vesting date, one-third (1/3rd) of the RSUs subject to the award will vest each year following the RSU Grant Date on the same day of the month as the RSU Grant Date (or, if there is no corresponding day in a particular month, then the last day of the month) over three (3) years. "RSU Grant Date" shall mean January 2, 2024. Subject to the Reporting Person continuing to be a Service Provider (as defined in the Issuer's 2022 Equity Incentive Plan) through each applicable vesting date, one-third (1/3rd) of the RSUs subject to the award will vest each year following the RSU Grant Date on the same day of the month as the RSU Grant Date (or, if there is no corresponding day in a particular month, then the last day of the month) over three (3) years. "RSU Grant Date" shall mean January 3, 2023. /s/ Michelle Gilson 2024-01-04