Arm 3: DYKSTRA KAREN E transacted N/A shares of Ordinary Shares at… (Mar 18, 2026)

=== SEC Form 3 — Statement of Changes in Beneficial Ownership === Document Type: 3 Period of Report: 2026-03-18 --- Issuer --- Name: ARM HOLDINGS PLC /UK (ARM) CIK: 0001973239 --- Reporting Owner --- Name: DYKSTRA KAREN E CIK: 0001198848 Role: Director --- Holdings --- [Holding #1] Security: Ordinary Shares Ownership: D (Direct) Footnotes: [F1] Ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), are held in the form of American Depositary Shares ("ADSs"). Each ADS represents 1 Ordinary Share. [Holding #2] Security: Ordinary Shares Ownership: I (Indirect) Footnotes: [F1] Ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), are held in the form of American Depositary Shares ("ADSs"). Each ADS represents 1 Ordinary Share. [Holding #3] Security: Restricted Stock Units Ownership: D (Direct) Footnotes: [F3] Each RSU represents the right to receive, following vesting, 1 Ordinary Share held in the form of an ADS. [F2] The restricted stock units ("RSUs") vested in full on May 15, 2025, but the ADSs have not been delivered pursuant to Ms. Dykstra's election to defer delivery until the date of termination of her service on the Board of Directors. [F2] The restricted stock units ("RSUs") vested in full on May 15, 2025, but the ADSs have not been delivered pursuant to Ms. Dykstra's election to defer delivery until the date of termination of her service on the Board of Directors. [F1] Ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), are held in the form of American Depositary Shares ("ADSs"). Each ADS represents 1 Ordinary Share. [Holding #4] Security: Restricted Stock Units Ownership: D (Direct) Footnotes: [F3] Each RSU represents the right to receive, following vesting, 1 Ordinary Share held in the form of an ADS. [F4] The RSUs will vest in full on May 15, 2026, subject to continued service to Arm Holdings plc, but the ADSs will not be delivered until the date of termination of Ms. Dykstra's service on the Board of Directors pursuant to her election to defer such delivery. [F4] The RSUs will vest in full on May 15, 2026, subject to continued service to Arm Holdings plc, but the ADSs will not be delivered until the date of termination of Ms. Dykstra's service on the Board of Directors pursuant to her election to defer such delivery. [F1] Ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), are held in the form of American Depositary Shares ("ADSs"). Each ADS represents 1 Ordinary Share. --- Footnotes (Complete Index) --- F1: Ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), are held in the form of American Depositary Shares ("ADSs"). Each ADS represents 1 Ordinary Share. F2: The restricted stock units ("RSUs") vested in full on May 15, 2025, but the ADSs have not been delivered pursuant to Ms. Dykstra's election to defer delivery until the date of termination of her service on the Board of Directors. F3: Each RSU represents the right to receive, following vesting, 1 Ordinary Share held in the form of an ADS. F4: The RSUs will vest in full on May 15, 2026, subject to continued service to Arm Holdings plc, but the ADSs will not be delivered until the date of termination of Ms. Dykstra's service on the Board of Directors pursuant to her election to defer such delivery. --- Signature --- /s/ /s/ George Kanelos, as Attorney-in-Fact for Karen E. Dykstra (2026-03-18)