The shareholders of Coordinated Auction Office in South East Europe are Transmission System Operators from the South East European region:

Croatia HOPS Hrvatski operator prijenosnog sustava d.o.o.
Bosnia and
Herzegovina
NOS-BiH Nezavisni operator sistema u Bosni i Hercegovini
Montenegro CGES Crnogorski elektroprenosni sistem AD
Albania OST Operatori i Sistemit te Transmetimit
Kosovo KOSTT Operator sistemi, transmisioni dhe tregu Sh.A.
Greece IPTO Independent Power Transmission Operator S.A.
Turkey TEIAS TÜRKIYE ELEKTRIK ILETIM A.S
FYROM MEPSO Македонски електропреносен систем оператор