SCHEDULE 13G/A

Arcellx Inc

Common Stock, $0.001 par value per share · CUSIP: 03940C100

Event date: 2025-12-31

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• RA Capital Management, L.P.

  Shares: 1,267,156.00 · Class: 2.2%

• Peter Kolchinsky

  Shares: 1,267,156.00 · Class: 2.2%

• Rajeev Shah

  Shares: 1,267,156.00 · Class: 2.2%

• RA Capital Healthcare Fund, L.P.

  Shares: 1,267,156.00 · Class: 2.2%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.