| Abbreviation | Definition |
|---|---|
| OGZD | Oao Gaz.ads |
| OIG | Oryx Intl.gwth. |
| OIH | Omega Ins. |
| OIL | Oilexco |
| OKEY | O'key Regs |
| OMG | Omg |
| OMI | Orosur Mining |
| OML | Old Mutual |
| OMZA | Omz Adr 144A |
| OMZD | Omz Adr Lvl 1 |
| ONL | On-line |
| OOA | Octopus Aim |
| OPAY | Optimal Payments, P.L.C. |
| OPE | Optare |
| OPG | Opg Power |
| OPM | 1PM, P.L.C. |
| OPP | Origo |
| OPTS | Optos |
| ORA | Ora Capital |
| ORCP | Oracle Coal |