| Term |
| OBAS - Optibase Ltd. |
| OBCI - Ocean Bio-Chem Inc. |
| OCCF - Optical Cable Corporation |
| OCCX - OccuLogix Inc. |
| OCFC - OceanFirst Financial Corp. |
| OCLS - Oculus Innovative Sciences Inc. |
| OCNF - OceanFreight Inc. |
| OCNW - Occam Networks Inc. |
| ODFL - Old Dominion Freight Line Inc. |
| ODSY - Odyssey Healthcare Inc. |
| OESX - Orion Energy Systems Inc. |
| OFIX - Orthofix International N.V. |
| OFLX - Omega Flex Inc. |
| OFSI - Omni Financial Services Inc. |
| OICO - O. I. Corporation |
| OIIM - O2Micro International Limited |
| OKSB - Southwest Bancorp Inc. |
| OLBK - Old Line Bancshares Inc. |
| OLCB - Ohio Legacy Corporation |
| OLGC - Orthologic Corp. |
| OMAB - Grupo Aeroportuario del Centro Norte S.A.B. de C.V. |
| OMCL - Omnicell Inc. |
| OMEX - Odyssey Marine Exploration Inc. |
| OMGI - Orion Marine Group Inc |
| OMNI - OMNI Energy Services Corp. |
| OMPI - Obagi Medical Products Inc. |
| OMRI - Omrix Biopharmaceuticals Inc. |
| OMTR - Omniture Inc. |
| ONAV - Omega Navigation Enterprises Inc. |
| ONCY - Oncolytics Biotech Inc. |
| ONEQ - Fidelity Nasdaq Composite Index Tracking Stock |
| ONFC - Oneida Financial Corp. |
| ONNN - ON Semiconductor Corporation |
| ONSM - Onstream Media Corporation |
| ONTY - Oncothyreon Inc . |
| ONVI - Onvia Inc. |
| ONXX - ONYX Pharmaceuticals Inc. |
| OPHC - OptimumBank Holdings Inc. |
| OPLK - Oplink Communications Inc. |
| OPMR - Optimal Group Inc. |
| OPNT - OPNET Technologies Inc. |
| OPOF - Old Point Financial Corporation |
| OPTC - Optelecom-NKF Inc. |
| OPTM - Optium Corporation |
| OPTR - Optimer Pharmaceuticals Inc. |
| OPTT - Ocean Power Technologies Inc. |
| OPTV - OpenTV Corp. |
| OPWV - Openwave Systems Inc |
| OPXA - Opexa Therapeutics Inc. |
| OPXAW - Opexa Therapeutics Inc. |
| OPXT - Opnext Inc. |
| ORBC - ORBCOMM Inc. |
| ORBK - Orbotech Ltd. |
| ORBT - Orbit International Corporation |
| ORCC - Online Resources Corporation |
| ORCD - Orchard Enterprises Inc (The) |
| ORCH - Orchid Cellmark Inc. |
| ORCL - Oracle Corporation |
| ORCT - Orckit Communications Limited |
| OREX - Orexigen Therapeutics Inc. |
| ORGN - Origen Financial Inc. |
| ORIT - Oritani Financial Corp. |
| ORLY - O Reilly Automotive Inc. |
| ORNG - Orange 21 Inc. |
| ORXE - Ore Pharmaceuticals Inc |
| OSBC - Old Second Bancorp Inc. |
| OSBCP - Old Second Bancorp Inc. |
| OSBK - Osage Bancshares Inc. |
| OSCI - Oscient Pharmaceuticals Corporation |
| OSHC - Ocean Shore Holding Co. |
| OSIP - OSI Pharmaceuticals Inc. |
| OSIR - Osiris Therapeutics Inc. |
| OSIS - OSI Systems Inc. |
| OSTE - Osteotech Inc. |
| OSTK - Overstock.com Inc. |
| OSUR - OraSure Technologies Inc. |
| OTEX - Open Text Corporation |
| OTIV - On Track Innovations Ltd |
| OTTR - Otter Tail Corporation |
| OUTD - Outdoor Channel Holdings Inc. |
| OVBC - Ohio Valley Banc Corp. |
| OVEN - TurboChef Technologies Inc. |
| OVRL - Overland Storage Inc. |
| OVTI - OmniVision Technologies Inc. |
| OXGN - OXiGENE Inc. |
| OXPS - optionsXpress Holdings Inc. |
| OYOG - OYO Geospace Corporation |
| OZRK - Bank of the Ozarks |
