The shareholders of Coordinated Auction Office in South East Europe are eight Transmission System Operators from the South East European region:
| Croatia |
 |
HOPS | Croatian Transmission System Operator Plc. |
|
Bosnia and Herzegovina |
 |
NOSBiH | 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. |
| Türkiye |
 |
TEIAS | Türkiye Elektrik İletim A.Ş. |
| North Macedonia |
 |
MEPSO | Оператор на електропреносниот систем на Република Северна Македонија |