INFORMATION CIRCULAR REGARDING THE VOLUNTARY TENDER OFFER ADDRESSED BY EURONEXT N.V. TO THE SHAREHOLDERS OF HELLENIC EXCHANGES-ATHENS STOCK EXCHANGE S.A. TO ACQUIRE ALL THE ORDINARY SHARES OF HELLENIC EXCHANGES-ATHENS STOCK EXCHANGE S.A. IN CONSIDERATION FOR 0.050 OF A NEW ORDINARY SHARE OF EURONEXT N.V. FOR ONE ORDINARY SHARE OF HELLENIC EXCHANGES-ATHENS STOCK EXCHANGE S.A.