Arm

=== 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: Abbey William CIK: 0001945497 Role: Officer (Chief Commercial Officer) --- 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: 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] This restricted stock unit ("RSU") award was granted on December 9, 2025. 30% will vest on each of November 15, 2026, and November 15, 2027, and the remaining 40% will vest on November 15, 2028, subject to continued service to Arm Holdings plc (the "Company"). [F2] This restricted stock unit ("RSU") award was granted on December 9, 2025. 30% will vest on each of November 15, 2026, and November 15, 2027, and the remaining 40% will vest on November 15, 2028, subject to continued service to Arm Holdings plc (the "Company"). [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. [F4] This RSU award was granted on May 1, 2025. 30% will vest on each of May 15, 2026 and May 15, 2027, and the remaining 40% will vest on May 15, 2028, subject to continued service to the Company. [F4] This RSU award was granted on May 1, 2025. 30% will vest on each of May 15, 2026 and May 15, 2027, and the remaining 40% will vest on May 15, 2028, subject to continued service to the Company. [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. [F5] This RSU award of 5,809 was granted on May 13, 2024, of which 30% already vested on May 15, 2025. 30% will vest on May 15, 2026 and 40% will vest on May 15, 2027, subject to continued service to the Company. [F5] This RSU award of 5,809 was granted on May 13, 2024, of which 30% already vested on May 15, 2025. 30% will vest on May 15, 2026 and 40% will vest on May 15, 2027, subject to continued service to the Company. [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 #5] 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. [F6] This RSU award was granted on May 23, 2023 and will vest on May 15, 2026, subject to continued service to the Company. [F6] This RSU award was granted on May 23, 2023 and will vest on May 15, 2026, subject to continued service to the Company. [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: This restricted stock unit ("RSU") award was granted on December 9, 2025. 30% will vest on each of November 15, 2026, and November 15, 2027, and the remaining 40% will vest on November 15, 2028, subject to continued service to Arm Holdings plc (the "Company"). F3: Each RSU represents the right to receive, following vesting, 1 Ordinary Share held in the form of an ADS. F4: This RSU award was granted on May 1, 2025. 30% will vest on each of May 15, 2026 and May 15, 2027, and the remaining 40% will vest on May 15, 2028, subject to continued service to the Company. F5: This RSU award of 5,809 was granted on May 13, 2024, of which 30% already vested on May 15, 2025. 30% will vest on May 15, 2026 and 40% will vest on May 15, 2027, subject to continued service to the Company. F6: This RSU award was granted on May 23, 2023 and will vest on May 15, 2026, subject to continued service to the Company. --- Signature --- /s/ /s/ George Kanelos, as Attorney-in-Fact for William Abbey (2026-03-18)