| O split history Realty Income Corp | NYSE | Financials |
| OABC split history OmniAmerican Bancorp, Inc. | NASDAQ | Financials |
| OAK split history Oaktree Capital Group LLC | NYSE | Financials |
| OAKS split history Five Oaks Investment Corp | NYSE | Financials |
| OAS split history Oasis Petroleum Inc. | NYSE | Energy |
| OB split history OneBeacon Insurance Group, Ltd. | NYSE | Financials |
| OBAF split history OBA Financial Services Inc | NASDAQ | Financials |
| OBAS split history Optibase Ltd | NASDAQ | Financials |
| OBCI split history Ocean Bio-Chem, Inc. | NASDAQ | Non-Cyclical Consumer Goods & Services |
| OBT split history Orbital Corporation Ltd. (ADR) | NYSEAMEX | Cyclical Consumer Goods & Services |
| OC split history Owens Corning | NYSE | Cyclical Consumer Goods & Services |
| OCC split history Optical Cable Corporation | NASDAQ | Technology |
| OCCF split history Optical Cable Corporation | NASDAQ | Technology |
| OCFC split history OceanFirst Financial Corp. | NASDAQ | Financials |
| OCIP split history OCI Partners LP | NYSE | Basic Materials |
| OCIR split history Oci Resources LP | NYSE | Basic Materials |
| OCLR split history Oclaro, Inc. | NASDAQ | Healthcare |
| OCLS split history Oculus Innovative Sciences, Inc. | NASDAQ | Healthcare |
| OCN split history Ocwen Financial Corp | NYSE | Financials |
| OCNF split history OceanFreight Inc. | NASDAQ | Industrials |
| OCNW split history Occam Networks, Inc. | NASDAQ | Technology |
| OCR split history Omnicare, Inc. | NYSE | Healthcare |
| OCRX split history Ocera Therapeutics Inc | NASDAQ | Healthcare |
| OCUL split history Ocular Therapeutix Inc | NASDAQ | Healthcare |
| OCZ split history OCZ Technology Group Inc. | NASDAQ | Technology |
| ODC split history Oil-Dri Corporation of America | NYSE | Non-Cyclical Consumer Goods & Services |
| ODFL split history Old Dominion Freight Line | NASDAQ | Industrials |
| ODP split history Office Depot Inc | NASDAQ | Cyclical Consumer Goods & Services |
| ODSY split history Odyssey HealthCare, Inc. | NASDAQ | Healthcare |
| OEC split history Orion Engineered Carbons SARL | NYSE | Basic Materials |
| OEH split history Orient-Express Hotels Ltd. | NYSE | Services |
| OESX split history Orion Energy Systems, Inc. | NYSEMKT | Cyclical Consumer Goods & Services |
| OFC split history Corporate Office Properties Trust | NYSE | Financials |
| OFED split history Oconee Federal Financial | NASDAQ | Financials |
| OFG split history OFG Bancorp | NYSE | Financials |
| OFI split history Overhill Farms, Inc. | NYSEAMEX | Non-Cyclical Consumer Goods & Services |
| OFIX split history Orthofix International NV | NASDAQ | Healthcare |
| OFLX split history Omega Flex, Inc. | NASDAQ | Industrials |
| OFS split history OFS Capital Corp | NASDAQ | Financials |
| OGE split history OGE Energy Corp. | NYSE | Utilities |
| OGEN split history Oragenics Inc | NYSEMKT | Healthcare |
| OGS split history ONE Gas Inc | NYSE | Utilities |
| OGXI split history OncoGenex Pharmaceuticals Inc | NASDAQ | Healthcare |
| OHAI split history OHA Investment Corp | NASDAQ | Financials |
| OHGI split history One Horizon Group Inc | NASDAQ | Technology |
| OHI split history Omega Healthcare Investors Inc | NYSE | Financials |
| OHRP split history OHR Pharmaceutical Inc | NASDAQ | Healthcare |
| OI split history Owens-Illinois Inc | NYSE | Basic Materials |
| OIA split history Invesco Municipal Inc Opp Trust II | NYSE | Financials |
| OIB split history Invesco Municipal Inc Opp Trust II | NYSE | Financials |
| OIBR split history Oi SA (ADR) | NYSE | Telecommunications Services |
| OIC split history Invesco Municipal Inc Opp Trust III | NYSE | Financials |
| OICO split history O.I. Corporation | NASDAQ | Technology |
| OII split history Oceaneering International | NYSE | Energy |
| OIIM split history O2Micro International Limited (ADR) | NASDAQ | Technology |
| OIL split history iPath S&P GSCI Crude Oil Total Return | NYSE | Financials |
| OILT split history Oiltanking Partners LP | NYSE | Energy |
| OINK split history Tianli Agritech, Inc. | NASDAQ | Non-Cyclical Consumer Goods & Services |
| OIS split history Oil States International, Inc. | NYSE | Energy |
| OKE split history ONEOK, Inc. | NYSE | Utilities |
| OKS split history Oneok Partners LP | NYSE | Utilities |
| OKSB split history Southwest Bancorp, Inc. | NASDAQ | Financials |
| OLA split history Old Mutual Claymore Long Short Fund | NYSE | Financials |
| OLBK split history Old Line Bancshares, Inc. (MD) | NASDAQ | Financials |
| OLCB split history Ohio Legacy Corp | NASDAQ | Financials |
| OLED split history Universal Display Corporation | NASDAQ | Technology |
| OLN split history Olin Corporation | NYSE | Basic Materials |
| OLP split history One Liberty Properties, Inc. | NYSE | Financials |
| OMAB split history Grupo Aeroportuario del Centro Nort(ADR) | NASDAQ | Industrials |
| OMAM split history OM Asset Management PLC | NYSE | Financials |
| OMC split history Omnicom Group Inc. | NYSE | Cyclical Consumer Goods & Services |
| OMCL split history Omnicell, Inc. | NASDAQ | Healthcare |
| OME split history Omega Protein Corporation | NYSE | Non-Cyclical Consumer Goods & Services |
| OMED split history Oncomed Pharmaceuticals Inc | NASDAQ | Healthcare |
| OMER split history Omeros Corporation | NASDAQ | Healthcare |
| OMEX split history Odyssey Marine Exploration Inc | NASDAQ | Industrials |
| OMG split history OM Group, Inc. | NYSE | Basic Materials |
| OMI split history Owens & Minor, Inc. | NYSE | Healthcare |
| OMN split history OMNOVA Solutions Inc. | NYSE | Basic Materials |
| OMNI split history OMNI Energy Services Corp. | NASDAQ | Energy |
| OMPI split history Obagi Medical Products, Inc. | NASDAQ | Healthcare |
| OMTH split history Omthera Pharmaceuticals Inc | NASDAQ | Industrials |
| OMX split history OfficeMax Inc | NYSE | Non-Cyclical Consumer Goods & Services |
| ONAV split history Omega Navigation Enterprises, Inc. | NASDAQ | Industrials |
| ONB split history Old National Bancorp | NASDAQ | Financials |
| ONCY split history Oncolytics Biotech, Inc. (USA) | NASDAQ | Healthcare |
| ONE split history Higher One Holdings, Inc | NYSE | Industrials |
| ONEQ split history Fidelity NASDAQ Comp. Index Trk Stk(ETF) | NASDAQ | Financials |
| ONFC split history Oneida Financial Corp | NASDAQ | Financials |
| ONNN split history ON Semiconductor Corp | NASDAQ | Technology |
| ONP split history Orient Paper Inc | NYSEMKT | Basic Materials |
| ONTX split history Onconova Therapeutics Inc | NASDAQ | Healthcare |
| ONTY split history Oncothyreon Inc (USA) | NASDAQ | Healthcare |
| ONVI split history Onvia, Inc. | NASDAQ | Industrials |
| ONVO split history Organovo Holdings Inc | NYSEMKT | Healthcare |
| ONXX split history Onyx Pharmaceuticals, Inc. | NASDAQ | Healthcare |
| OPAY split history Official Payments Holdings Inc | NASDAQ | Services |
| OPB split history Opus Bank | NASDAQ | Financials |
| OPEN split history OpenTable Inc | NASDAQ | Technology |
| OPHC split history OptimumBank Holdings, Inc. | NASDAQ | Financials |
| OPHT split history Ophthotech Corp | NASDAQ | Healthcare |
| OPK split history Opko Health Inc. | NYSE | Healthcare |
| OPLK split history Oplink Communications, Inc | NASDAQ | Technology |
| OPMR split history Optimal Group Inc. | NASDAQ | Services |
| OPNT split history OPNET Technologies, Inc. | NASDAQ | Technology |
| OPOF split history Old Point Financial Corporation | NASDAQ | Financials |
| OPTC split history Optelecom-NKF, Inc. | NASDAQ | Technology |
| OPTR split history Optimer Pharmaceuticals, Inc. | NASDAQ | Healthcare |
| OPTT split history Ocean Power Technologies Inc | NASDAQ | Utilities |
| OPWR split history Opower Inc | NYSE | Technology |
| OPWV split history Openwave Systems Inc. | NASDAQ | Technology |
| OPXA split history Opexa Therapeutics Inc | NASDAQ | Healthcare |
| OPXT split history Opnext, Inc. | NASDAQ | Technology |
| OPY split history Oppenheimer Holdings Inc. (USA) | NYSE | Financials |
| ORA split history Ormat Technologies, Inc. | NYSE | Utilities |
| ORAN split history Orange SA (ADR) | NYSE | Telecommunications Services |
| ORB split history Orbital Sciences Corp | NYSE | Industrials |
| ORBC split history ORBCOMM Inc | NASDAQ | Telecommunications Services |
| ORBK split history Orbotech Ltd | NASDAQ | Industrials |
| ORBT split history Orbit International Corp. | NASDAQ | Technology |
| ORC split history Orchid Island Capital Inc | NYSE | Financials |
| ORCC split history Online Resources Corporation | NASDAQ | Technology |
| ORCD split history Orchard Enterprises, Inc. | NASDAQ | Cyclical Consumer Goods & Services |
| ORCH split history Orchid Cellmark, Inc. | NASDAQ | Healthcare |
| ORCL split history Oracle Corporation | NYSE | Technology |
| ORCT split history Orckit Communications Ltd | NASDAQ | Technology |
| OREX split history Orexigen Therapeutics, Inc. | NASDAQ | Healthcare |
| ORI split history Old Republic International Corporation | NYSE | Financials |
| ORIG split history Ocean Rig UDW Inc | NASDAQ | Energy |
| ORIT split history Oritani Financial Corp. | NASDAQ | Financials |
| ORLY split history O'Reilly Automotive Inc | NASDAQ | Cyclical Consumer Goods & Services |
| ORM split history Owens Realty Mortgage Inc | NYSEMKT | Financials |
| ORMP split history Oramed Pharmaceuticals, Inc. | NASDAQ | Healthcare |
| ORN split history Orion Marine Group, Inc. | NYSE | Industrials |
| ORPN split history Bio Blast Pharma Ltd | NASDAQ | Healthcare |
| ORRF split history Orrstown Financial Services | NASDAQ | Financials |
| ORS split history Orsus Xelent Technologies Inc. | AMEX | Technology |
| OSBC split history Old Second Bancorp Inc. | NASDAQ | Financials |
| OSG split history Overseas Shipholding Group Inc. | NYSE | Industrials |
| OSH split history Orchard Supply Hardware Stores Corp | NASDAQ | Industrials |
| OSHC split history Ocean Shore Holding Co | NASDAQ | Financials |
| OSIP split history OSI Pharmaceuticals, Inc. | NASDAQ | Healthcare |
| OSIR split history Osiris Therapeutics, Inc. | NASDAQ | Healthcare |
| OSIS split history OSI Systems, Inc. | NASDAQ | Technology |
| OSK split history Oshkosh Corporation | NYSE | Industrials |
| OSN split history Ossen Innovation Co Ltd (ADR) | NASDAQ | Basic Materials |
| OSTE split history Osteotech, Inc. | NASDAQ | Healthcare |
| OSTK split history Overstock.com, Inc. | NASDAQ | Technology |
| OSUR split history OraSure Technologies, Inc. | NASDAQ | Healthcare |
| OTE split history Hellenic Telecom Organization S.A. (ADR) | NYSE | Services |
| OTEX split history Open Text Corporation (USA) | NASDAQ | Technology |
| OTIC split history Otonomy Inc | NASDAQ | Healthcare |
| OTIV split history On Track Innovations Ltd (USA) | NASDAQ | Technology |
| OTT split history Otelco Inc | NASDAQ | Services |
| OTTR split history Otter Tail Corporation | NASDAQ | Financials |
| OUTD split history Outdoor Channel Holdings, Inc. | NASDAQ | Services |
| OUTR split history Outerwall Inc | NASDAQ | Non-Cyclical Consumer Goods & Services |
| OVAS split history OvaScience Inc | NASDAQ | Healthcare |
| OVBC split history Ohio Valley Banc Corp. | NASDAQ | Financials |
| OVLY split history Oak Valley Bancorp(NDA) | NASDAQ | Financials |
| OVRL split history Overland Storage Inc | NASDAQ | Technology |
| OVTI split history OmniVision Technologies, Inc. | NASDAQ | Technology |
| OWW split history Orbitz Worldwide, Inc. | NYSE | Cyclical Consumer Goods & Services |
| OXBT split history Oxygen Biotherapeutics, Inc. | NASDAQ | Healthcare |
| OXF split history Oxford Resource Partners, LP | NYSE | Energy |
| OXFD split history Oxford Immunotec Global PLC | NASDAQ | Healthcare |
| OXGN split history OXiGENE Inc | NASDAQ | Healthcare |
| OXLC split history Oxford Lane Capital Corp | NASDAQ | Financials |
| OXM split history Oxford Industries Inc | NYSE | Cyclical Consumer Goods & Services |
| OXPS split history optionsXpress Holdings, Inc. | NASDAQ | Financials |
| OXY split history Occidental Petroleum Corporation | NYSE | Energy |
| OYOG split history OYO Geospace Corporation | NASDAQ | Technology |
| OZM split history Och-Ziff Capital Management Group LLC | NYSE | Financials |
| OZRK split history Bank Of The Ozarks Inc | NASDAQ | Financials |