Masayoshi Son details Arm (NASDAQ: ARM) stake via SoftBank unit

Rhea-AI Filing Summary

ARM Holdings plc director Masayoshi Son filed an initial ownership report showing no Ordinary Shares held directly in his name. A footnote explains that 922,733,999 Ordinary Shares of Arm Holdings plc are held of record by Kronos II LLC, an indirect wholly owned subsidiary of SoftBank Group Corp. Son serves as Representative Director, Corporate Officer, Chairman and CEO of SoftBank Group and expressly disclaims beneficial ownership of the Ordinary Shares held by Kronos II.

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

MASAYOSHI SON

(Last) (First) (Middle)

1-7-1 KAIGAN

MINATO-KU

(Street)

TOKYO 105-7537

(City) (State) (Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
03/18/2026

3. Issuer Name and Ticker or Trading Symbol
ARM HOLDINGS PLC /UK [ ARM ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Ordinary Shares	0(1)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 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

	/s/ George Kanelos, as Attorney-in-Fact for Masayoshi Son	03/18/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 3: SEC 1473 (03-26)

FAQ

What does Masayoshi Son’s Form 3 filing for ARM (ARM) show?

The Form 3 shows Masayoshi Son reports no Ordinary Shares of Arm Holdings plc held directly in his name. A large block of 922,733,999 Ordinary Shares is held by Kronos II LLC, an indirect wholly owned subsidiary of SoftBank Group Corp., and he disclaims beneficial ownership.

Who actually holds the 922,733,999 ARM (ARM) Ordinary Shares mentioned?

The 922,733,999 Ordinary Shares of Arm Holdings plc are held of record by Kronos II LLC. Kronos II LLC is an indirect wholly owned subsidiary of SoftBank Group Corp., which means the position is associated with SoftBank’s corporate structure rather than Masayoshi Son personally.

How is Masayoshi Son related to SoftBank Group in the ARM (ARM) filing?

Masayoshi Son is identified as Representative Director, Corporate Officer, Chairman and CEO of SoftBank Group Corp. This explains his reporting relationship to the large Arm Holdings plc stake held by Kronos II LLC, SoftBank’s indirect wholly owned subsidiary, in the Form 3 disclosure.

Does Masayoshi Son claim beneficial ownership of ARM (ARM) shares?

No, Masayoshi Son specifically disclaims beneficial ownership of the Ordinary Shares held by Kronos II LLC. Even though he leads SoftBank Group Corp., the filing clarifies that the substantial Arm Holdings plc stake at Kronos II is not reported as his personal beneficial ownership.

What type of ARM (ARM) security is referenced in Masayoshi Son’s Form 3?

The filing references Ordinary Shares of Arm Holdings plc with a nominal value of 0.001 GBP per share. It also notes these Ordinary Shares may be represented by American Depositary Shares, each American Depositary Share representing one Ordinary Share under the described structure.

Are ARM (ARM) American Depositary Shares mentioned in this Form 3?

Yes, the footnote states the Ordinary Shares held by Kronos II LLC may be represented by American Depositary Shares. Each American Depositary Share represents one Ordinary Share of Arm Holdings plc, linking the London-based Ordinary Shares to U.S.-traded depositary instruments.