Son Masayoshi - 18 Mar 2026 Form 3 Insider Report for ARM HOLDINGS PLC /UK (ARM)

Role: Director
Signature: /s/ George Kanelos, as Attorney-in-Fact for Masayoshi Son
Issuer symbol: ARM
Transactions as of: 18 Mar 2026
Net transactions value: $0
Form type: 3
Filing time: 18 Mar 2026, 16:50:58 UTC
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
MASAYOSHI SON	Director	1-7-1 KAIGAN, MINATO-KU, TOKYO, JAPAN	/s/ George Kanelos, as Attorney-in-Fact for Masayoshi Son	18 Mar 2026	0001065520

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	ARM	Ordinary Shares						0	18 Mar 2026	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	922,733,999 ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), of Arm Holdings plc are held of record by Kronos II LLC ("Kronos II"), an indirect wholly-owned subsidiary of SoftBank Group Corp. ("SoftBank Group"). The Ordinary Shares held by Kronos II may be represented by American Depositary Shares, each representing one Ordinary Share. The reporting person is Representative Director, Corporate Officer, Chairman and CEO of SoftBank Group. The reporting person disclaims beneficial ownership of the Ordinary Shares held by Kronos II.

Content

922,733,999 ordinary shares, nominal value 0.001 GBP per share ("Ordinary Shares"), of Arm Holdings plc are held of record by Kronos II LLC ("Kronos II"), an indirect wholly-owned subsidiary of SoftBank Group Corp. ("SoftBank Group"). The Ordinary Shares held by Kronos II may be represented by American Depositary Shares, each representing one Ordinary Share. The reporting person is Representative Director, Corporate Officer, Chairman and CEO of SoftBank Group. The reporting person disclaims beneficial ownership of the Ordinary Shares held by Kronos II.

Remarks:

Exhibit 24 - Power of Attorney