| Abbreviation | Definition |
|---|---|
| OIP | Orion Oil & Gas Corporation |
| OLE | Oromin Explorations Ltd. |
| OLE | Oromin Explorations LTD. (de-listed) |
| OLE | Oromin Explorations LTD. (de-listed) |
| OMG | OPMEDIC Group Inc. |
| OMG | OPMEDIC Group Incorporated (de-listed) |
| OMG | OPMEDIC Group Incorporated (de-listed) |
| ONC | Oncolytics Biotech Inc. |
| ONC | Oncolytics Biotech Incorporated |
| ONE | 01 Communique Laboratory Inc. |
| ONEX | ONEX Corporation Subordinate Voting Shares |
| ONR | Open Range Energy Corporation |
| OPC | OPTI Canada, Inc. |
| OPM | Opta Minerals Inc. |
| OPM | Opta Minerals Incorporated (de-listed) |
| OPM | Opta Minerals Incorporated (de-listed) |
| ORA | Aura Minerals Inc. |
| ORA | Aura Minerals Incorporated |
| ORE | Orezone Gold Corporation |
| ORL | Orocobre Limited |