| Abbreviation | Definition |
|---|---|
| OIIC | Oil Industry Investment Company |
| OIIC | Ontario Immigrant Investor Corporation |
| OIIT | Office of International Investment and Trade |
| OIK | Oppenheim Immobilien-Kapitalanlagegesellschaft GmbH (German: Oppenheim Real Estate Investment Company; Oppenheim, Germany) |
| OIO | Overseas Investment Office |
| OIPI | Office of Intermodal Planning and Investment |
| OIZ | Official Investment Zone |
| OLC | Online Loan Capital |
| OLPA | Optional Local Purpose Assessment |
| OMERS | Ontario Municipal Employee Retirement System |
| OMI | Optimising Marketing Investment |
| OMIG | Old Mutual Investment Group |
| OPIP | Office Of Private Investment Promotion |
| OPIS | Offshore Portfolio Investment Strategy |
| OPLC | Office of Prices and Living Conditions |
| OPMI | Outside Passive Minority Investor |
| OPO | Online Public Offering |
| OTO | Own The Outcome |
| PABD | Project And Business Developments |
| PAIC | Pan African Investment Code |