| Company name | Reg. code |
|---|---|
| OPETRON OÜ | 12476601 |
| OPETRON ENERGIA OÜ | 12207930 |
| OPETRON CAPITAL OÜ (former name Opetron Bankers Capital) | 12471101 |
| OPETRON KINNISVARA OÜ | 12477032 |
| OPESTON OÜ | 16901165 |
| OPTERON OÜ | 11126365 |
| PETRONE & PETRONE OÜ | 12983278 |
| POCTRON OÜ | 17016703 |
| ELETRON OÜ | 16072415 |
| SEPTRON OÜ | 17151536 |
| KOMETRON OÜ kustutatud (former name OÜ Business Trading) | 12982445 |
| APEIRON OÜ kustutatud | 16007085 |
| SPECTRON OÜ | 17396172 |
| ONERTON OÜ | 10817956 |
| COPITRON OÜ | 14163556 |
| UPSTRON OÜ | 11621685 |
| OMITRON OÜ | 10314219 |
| MONETRON OÜ (former name Moneenu OÜ) | 12835603 |
| VOLETRON OÜ | 10465651 |
| PETRONA OÜ kustutatud | 11318337 |
| PETRON-REN OÜ | 12352595 |
| NETRON OÜ kustutatud | 14795026 |
| OMERON OÜ | 16140016 |
| OLERON OÜ kustutatud | 10689273 |
| METRON OÜ | 14381164 |
| SETRON OÜ kustutatud (former name Setron UÜ) | 16028472 |
| OSTRON OÜ kustutatud | 14957799 |
| ORETON OÜ (former name Oreton UÜ) | 14704526 |
| OBERON OÜ | 17173443 |
| PETKON OÜ | 12805364 |
| OPTION OÜ | 14067781 |
| PETSON OÜ | 12220149 |
| APEIRON HOLDING OÜ | 16714463 |
| OBERRON CONSULTING OÜ kustutatud | 14630800 |
| PETRONI HOLDING OÜ kustutatud | 12118528 |
| PETRONE PRINT OÜ | 11351624 |
| ONERTON LOGISTICS OÜ | 12715566 |
| OPTION ONE OÜ | 14466104 |
| OPTION OMS OÜ kustutatud | 12147257 |
| FINE PETROL OÜ | 10619746 |
| PIRY-PETROL OÜ | 11515150 |
| OBERON GRUPP OÜ kustutatud | 11970894 |
| OBERON VA OÜ kustutatud | 10110037 |
| METRON INVEST OÜ | 10806388 |
| NETRON BALTIC OÜ | 11895342 |
| OVERON EHITUS OÜ kustutatud | 11270257 |
| IPTRON.NET OÜ | 12145583 |
| 3RD OPTION OÜ | 14922246 |
| ESTONIAN PETROL OÜ | 10949171 |
| PETROV KNV OÜ | 16301459 |