X0508 4 2026-01-13 0001786205 Arcellx, Inc. ACLX 0001789632 Heery Christopher C/O ARCELLX, INC. 800 BRIDGE PARKWAY REDWOOD CITY CA 94065 false true false false CHIEF MEDICAL OFFICER false Common Stock 2026-01-03 4 M false 16520 0 A 30135 D Common Stock 2026-01-13 4 S false 7437 65.5120 D 29631 D Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock. Vesting of these RSUs previously reported in the Form 4 filed January 6, 2026. Represents a broker-assisted sale to satisfy the Reporting Person's tax withholding obligations in connection with the vesting of restricted stock units. The price reported reflects the weighted average sales price. These shares were sold in multiple transactions at prices that were not available from the broker at the time of filing. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price. /s/ Michelle Gilson, as Attorney-in-Fact 2026-01-13