| Otonomy Inc (OTIC) NASDAQ - National Association of Securities Dealers Automated Quotations | |
| Orient Bell Ltd (ORIENTBELL) NSE - National Stock Exchange of India | |
| Ocado Group PLC (OCDO) LSE - London Stock Exchange | |
| Old Mutual plc (OML) LSE - London Stock Exchange | |
| Obrascon Huarte Lain SA (OHL) BME - Bolsa de Madrid Exchange | |
| Olympic Entertainment Group AS (OEG1T) TAL - Tallinn NASDAQ OMX | |
| Osisko gold royalties Ltd (OR) TSE - Toronto Stock Exchange | |
| Organovo Holdings Inc (ONVO) NYSEMKT - NYSE MKT LLC | |
| Ortel Communications Ltd (ORTEL) BSE - Bombay Stock Exchange | |
| Orchid Pharma Ltd (ORCHIDPHAR) NSE - National Stock Exchange of India | |
| OncoSec Medical Inc (ONCS) NASDAQ - National Association of Securities Dealers Automated Quotations | |
| Orion Energy Systems, Inc. (OESX) NASDAQ - National Association of Securities Dealers Automated Quotations | |
| OCEANIC RESEARCH (ORRV) OTCMKTS - OTC Markets | |
| OPAP(ORG OF FOOTB) (GOFPY) OTCMKTS - OTC Markets | |
| ORCA GOLD INC (CANWF) OTCMKTS - OTC Markets | |