Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARES

1. Identity of the issuer or the underlying issuerof existing shares to which voting rights areattached: ii

Impax Asset Management Group plc (IPX:LSE)

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

x

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

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

An event changing the breakdown of voting rights

Other (please specify):

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

Sanne Trust Company Limited as trustee of the Impax Group plc Employee Benefit Trust 2012

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

Shares held by Greenwood Nominees Limited

5. Date of the transaction and date onwhich the threshold is crossed orreached: v

31 May 2013

6. Date on which issuer notified:

3 June 2013

7. Threshold(s) that is/are crossed orreached: vi, vii

13%

8. Notified details:

A: Voting rights attached to shares viii, ix

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 x

Direct

Direct xi

Indirect xii

Direct

Indirect

GB0004905260

16,594,043

16,594,043

15,584,143

15,584,143

12.20

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

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

% of votingrights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

15,584,143

12.20

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

Proxy Voting:

10. Name of the proxy holder:

11. Number of voting rights proxy holder will ceaseto hold:

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

13. Additional information:

The Impax Asset Management Group plc Employee Benefit Trust 2012 (the "Trust") has released shares to beneficiaries of the Trust and purchased shares resulting in the Trust holdings dropping through the 13% level.

14. Contact name:

Colum Spillane

15. Contact telephone number:

01534 750598