TR-1: NOTIFICATION OF MAJOR INTEREST 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 the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

Yes 

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

No 

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

No 

An event changing the breakdown of voting rights

No 

Other (please specify):

No 

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

Ameriprise Financial, Inc. and its group

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

See additional information under 13.

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

27 November 2009

6. Date on which issuer notified:

30 November 2009

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

Above the threshold of 5% 

8. Notified details:

A: Voting rights attached to shares

Class/type of
shares

if possible using
the 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

% of voting rights

Direct

Direct

Indirect

Direct

Indirect

 N/A

 N/A

 2,326,646

 2,326,646

 61,619,967

 0.181%

 4.815%

 GB0000595859

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial
instrument

Expiration
date

Exercise/ 
Conversion 
Period

Number of voting
rights that may be
acquired if the
instrument is
exercised/ converted.

% of voting
rights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial
instrument

Exercise 
price

Expiration 
date

Exercise/
Conversion 
period

Number of voting 
rights instrument 
refers to

% of voting rights

 CFD

 431,376

Nominal

Delta

 0.034%

Total (A+B+C)

Number of voting rights

Percentage of voting rights

 64,377,989

 5.030%

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

Ameriprise Financial, Inc. which through intermediate holding companies controls the voting rights of Threadneedle Management Luxembourg S.A. and Threadneedle Asset Management Holdings Ltd, which itself controls the voting rights of Threadneedle Asset Management Ltd, Threadneedle International Ltd and Threadneedle Pensions Ltd. 

Proxy Voting:

10. Name of the 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:

Registered Owner

14. Contact name:

 JOANNE O'SULLIVAN

15. Contact telephone number:

 +44 (0)20 7464 5000