Karen E. Dykstra - 18 Mar 2026 Form 3 Insider Report for ARM HOLDINGS PLC /UK (ARM)

Reporting relationship: Director
Issuer ticker: ARM
Reported as of: 18 Mar 2026
Net transaction value: $0
SEC form: 3
Accepted by SEC: 18 Mar 2026, 16:59:30 UTC
Prior SEC filing: 06 Jan 2026
Next SEC filing: 03 Apr 2026
Source filing: View source filing
Reporting owner signature: /s/ George Kanelos, as Attorney-in-Fact for Karen E. Dykstra

Key filing fact

Karen E. Dykstra filed Form 3 for ARM HOLDINGS PLC /UK (ARM) on 18 Mar 2026.

Key facts

This page summarizes Karen E. Dykstra's Form 3 filing for ARM HOLDINGS PLC /UK (ARM).
0 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 18 Mar 2026, 16:59.

Change

Previous filing in this sequence was filed on 06 Jan 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Official SEC source

Ownership activity is grounded in SEC Form 3 disclosures.

View source filing

Reporting Owners (1)

CIK 0001198848 Primary reporting owner

DYKSTRA KAREN E

Relationship: Director
Address: C/O ARM HOLDINGS PLC, 110 FULBOURN ROAD, CAMBRIDGE, UNITED KINGDOM
Signature: /s/ George Kanelos, as Attorney-in-Fact for Karen E. Dykstra
Signature date: 18 Mar 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

ARM holding

Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 13,002
Date: 18 Mar 2026
Ownership: Direct
Footnotes: F1

ARM holding

Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 707
Date: 18 Mar 2026
Ownership: By Spouse
Footnotes: F1

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

ARM holding Derivative

Restricted Stock Units

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 18 Mar 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 2,130
Exercise price
Footnotes: F1, F2, F3

ARM holding Derivative

Restricted Stock Units

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 18 Mar 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 2,141
Exercise price
Footnotes: F1, F3, F4

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 4 footnotes

Footnote 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.

Footnote 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.

Footnote F3

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

Footnote 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.

SEC remarks

Exhibit 24 - Power of Attorney