Holding(s) in Company

For filings with the FSA include the annex

For filings with issuer exclude the annex 

TR-1: Notifications of Major Interests in Shares

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached:

ARM Holdings PLC

2. Reason for notification (yes/no)

An acquisition or disposal of voting rights

X

An acquisition or disposal of financial instruments which may result in the acquisition of shares already issued to which voting rights are attached 

An event changing the breakdown of voting rights

Other (please specify):______________

3. Full name of person(s) subject to notification obligation:

Thornburg Investment Management Inc.

4. Full name of shareholder(s) (if different from 3):

N/A

5. Date of transaction (and date on which the threshold is crossed or reached if different):

21/4/09

6. Date on which issuer notified:

24/4/09

7. Threshold(s) that is/are crossed or reached:

Under 10%

8: Notified Details

A: Voting rights attached to shares

Class/type of shares

If possible use ISIN code

Situation previous to the triggering transaction

Resulting situation after the triggering transaction

Number of shares

Number of voting rights

Number of shares

Number of voting rights

Percentage of voting rights

Direct

Indirect

Direct

Indirect

ORD

GB0000595859

ADR

US0420681068

Below 10%

Below 10%

Below 10%

Below 10%

N/A

N/A

95,008,661

10,016,990

N/A

7.67%

2.24%

B: Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date

Exercise/ conversion period/date 

No. of voting rights that may be acquired (if the instrument exercised/converted)

Percentage of voting rights

N/A

Total (A+B)

Number of voting rights

Percentage of voting rights

105,025,651

9.91%

9. Chain of controlled undertakings through which the voting rights and /or the financial instruments are effectively held, if applicable:

Thornburg Investment Management holds these shares as dicretionary Investment Manager.

Proxy Voting:

10. Name of proxy holder:

N/A

11. Number of voting rights proxy holder will cease to hold:

N/A

12. Date on which proxy holder will cease to hold voting rights:

N/A

13. Additional information:

14 Contact name:

Joanne O'Sullivan

15. Contact telephone number: