| Abbreviation | Definition |
|---|---|
| ORN | ORN |
| ORO | Oroya Mining Ltd |
| ORS | Octagonal Resources Limited |
| ORX | Orrex Resources Ltd |
| OSH | Oil Search Ltd (PNG) |
| OSHKMC | Oil Search Limited |
| OSHKOB | Oil Search Limited |
| OSHKOP | Oil Search Limited |
| OSHKRA | Oil Search Limited |
| OSHKRB | Oil Search Limited |
| OSHKRE | Oil Search Limited |
| OSHKRG | Oil Search Limited |
| OSHKRP | Oil Search Limited |
| OSHKRQ | Oil Search Limited |
| OSHKRR | Oil Search Limited |
| OSHKZD | Oil Search Ltd (PNG) |
| OSHKZE | Oil Search Ltd (PNG) |
| OST | Onesteel Ltd |
| OSTKMC | Onesteel Limited |
| OSTKMD | Onesteel Limited |