SEC FORM 3

SEC FORM 3SEC 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^*

Grisenthwaite Richard Roy

(Last)

(First)

(Middle)

C/O ARM HOLDINGS PLC

110 FULBOURN ROAD

(Street)

CAMBRIDGE

CB1 9NJ

(City)

(State)

(Zip)

UNITED KINGDOM

(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)

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

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⁽¹⁾	326	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)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	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)
Restricted Stock Units	⁽²⁾	⁽²⁾	Ordinary Shares⁽¹⁾	36,005	⁽³⁾	D
Restricted Stock Units	⁽⁴⁾	⁽⁴⁾	Ordinary Shares⁽¹⁾	6,820	⁽³⁾	D
Restricted Stock Units	⁽⁴⁾	⁽⁴⁾	Ordinary Shares⁽¹⁾	48,652	⁽³⁾	D
Restricted Stock Units	⁽⁵⁾	⁽⁵⁾	Ordinary Shares⁽¹⁾	3,805	⁽³⁾	D
Restricted Stock Units	⁽⁶⁾	⁽⁶⁾	Ordinary Shares⁽¹⁾	4,352	⁽³⁾	D

Explanation of Responses:

1. 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.

2. 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").

3. Each RSU represents the right to receive, following vesting, 1 Ordinary Share held in the form of an ADS.

4. 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.

5. This RSU award of 5,435 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.

6. This RSU award was granted on May 23, 2023, and will vest on May 15, 2026, subject to continued service to the Company.

Remarks:

Exhibit 24 - Power of Attorney

	/s/ George Kanelos, as Attorney-in-Fact for Richard Roy Grisenthwaite	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)

SEC Form 3 filed by new insider Grisenthwaite Richard Roy