| Abbreviation | Definition |
|---|---|
| OSTKMQ | Onesteel Limited |
| OSTKOF | Onesteel Limited |
| OSTKOG | Onesteel Limited |
| OSTKOP | Onesteel Limited |
| OSTKOQ | Onesteel Limited |
| OSTKRB | Onesteel Limited |
| OSTKRP | Onesteel Limited |
| OSTKRQ | Onesteel Limited |
| OSTKRR | Onesteel Limited |
| OTC | Otoc Limited |
| OTE | Otis Energy Limited |
| OTEO | Otis Energy Limited |
| OTH | Onthehouse Holdings Limited |
| OTI | Oriental Technologies Investment Ltd |
| OUM | OUM |
| OVR | Overland Resources Ltd |
| OXX | Octanex N.l. |
| OXXCA | Octanex N.l. |
| OYM | Olympus Pacific Minerals Inc |
| OZB | Oz Brewing Ltd |