| Abbreviation | Definition |
|---|---|
| ORE | Orogen Gold |
| ORM | Ormonde Mining |
| ORSD | Orascom Gdr |
| ORT | Ortus Vct |
| OS | Ordinary Shares |
| OSEC | Oct Sec Aim |
| OSG | Opsec |
| OSGA | Opsec Sec Assd |
| OSU | Orsu Metals |
| OTC | Ortac Resources, LTD. |
| OTE | O Twelve Estate |
| OTES | Ote Ads |
| OTLD | Orascom Tel. S |
| OTM | Ottoman |
| OTPD | Otp Bank Gdr's' |
| OTT | Oxf.tech 3 Vct |
| OTV | Otium Ventures |
| OTV1 | Octopus T. 1 |
| OTV2 | Octopus T. 2 |
| OTV3 | Octopus T. 3 |