Holding(s) in Company

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 event changing the breakdown of voting rights

NO

Other (please specify):

N/A

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

JANUS CAPITAL MANAGEMENT LLC

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

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

14 FEBRUARY 2011

6. Date on which issuer notified:

15 FEBRUARY 2011

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

6%

8. Notified details:

A: Voting rights attached to shares

Class/type ofshares

if possible usingthe ISIN CODE

Situation previousto the triggeringtransaction

Resulting situation after the triggering transaction

NumberofShares

NumberofVotingRights

Numberof shares

Number of votingrights

% of voting rights

Direct

Indirect

Direct

Indirect

85,004,732

85,004,732

79,045,291

79,045,291

5.98%

GB0000595859

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate

Exercise/ConversionPeriod

Number of votingrights that may beacquired if theinstrument isexercised/ converted.

% of votingrights

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

Resulting situation after the triggering transaction

Type of financialinstrument

Exerciseprice

Expirationdate

Exercise/Conversionperiod

Number of votingrights instrumentrefers to

% of voting rights

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

79,045,291

5.88%

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

Proxy Voting:

10. Name of the proxy holder:

JANUS CAPITAL MANAGEMENT LLC

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

5,959,441

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

14 FEBRUARY 2011

13. Additional information:

14. Contact name:

JOANNE O'SULLIVAN

15. Contact telephone number:

0044 1223 406122