| OI | O-I Glass Inc. | consumer-discretionary | 67 |
| ORLY | O'Reilly Automotive Inc. | consumer-discretionary | 44 |
| OVLY | Oak Valley Bancorp | finance | 1 |
| OACC | Oaktree Acquisition Corp. III Life Sciences | finance | 12 |
| OCSL | Oaktree Specialty Lending Corporation | finance | 0 |
| OTLY | Oatly Group AB | consumer-staples | 46 |
| OCEA | Ocean Biomedical Inc. | health-care | 6 |
| OPTT | Ocean Power Technologies Inc. | utilities | 4 |
| OII | Oceaneering International Inc. | energy | 17 |
| OCFC | OceanFirst Financial Corp. | finance | 0 |
| OCGN | Ocugen Inc. | health-care | 0 |
| OCUL | Ocular Therapeutix Inc. | health-care | 27 |
| OCS | Oculis Holding AG | health-care | 10 |
| ODD | ODDITY Tech Ltd. | consumer-discretionary | 5 |
| OMEX | Odyssey Marine Exploration Inc. | consumer-discretionary | 6 |
| OPAD | Offerpad Solutions Inc. | finance | 0 |
| OFG | OFG Bancorp | finance | 3 |
| OFS | OFS Capital Corporation | finance | 0 |
| OGE | OGE Energy Corp | utilities | 2 |
| OVBC | Ohio Valley Banc Corp. | finance | 3 |
| OMH | Ohmyhome Limited | finance | 6 |
| OIS | Oil States International Inc. | industrials | 8 |
| ODC | Oil-Dri Corporation Of America | consumer-discretionary | 2 |
| ECO | Okeanis Eco Tankers Corp. | consumer-discretionary | 1 |
| OKLO | Oklo Inc. | utilities | 43 |
| OKTA | Okta Inc. | technology | 62 |
| OKYO | OKYO Pharma Limited | health-care | 2 |
| OLPX | Olaplex Holdings Inc. | consumer-discretionary | 68 |
| ODFL | Old Dominion Freight Line Inc. | industrials | 47 |
| OMCC | Old Market Capital Corporation | finance | 2 |
| ONB | Old National Bancorp | finance | 83 |
| ORI | Old Republic International Corporation | finance | 35 |
| OSBC | Old Second Bancorp Inc. | finance | 0 |
| OLMA | Olema Pharmaceuticals Inc. | health-care | 35 |
| OLN | Olin Corporation | industrials | 9 |
| OLLI | Ollie's Bargain Outlet Holdings Inc. | consumer-discretionary | 6 |
| ZEUS | Olympic Steel Inc. | industrials | 1 |
| OFLX | Omega Flex Inc. | industrials | 4 |
| OHI | Omega Healthcare Investors Inc. | real-estate | 0 |
| OMER | Omeros Corporation | health-care | 1 |
| OABI | OmniAb Inc. | health-care | 1 |
| OMCL | Omnicell Inc. | technology | 3 |
| OMC | Omnicom Group Inc. | consumer-discretionary | 80 |
| ONON | On Holding AG | consumer-discretionary | 11 |
| ON | ON Semiconductor Corporation | technology | 0 |
| ONCY | Oncolytics Biotech Inc. | health-care | 1 |
| ONCO | Onconetix Inc. | health-care | 10 |
| ONDS | Ondas Holdings Inc. | technology | 1 |
| OGS | ONE Gas Inc. | utilities | 10 |
| OLP | One Liberty Properties Inc. | real-estate | 6 |
| OSS | One Stop Systems Inc. | technology | 1 |
| ONEG | OneConstruction Group Limited | consumer-discretionary | 4 |
| OMF | OneMain Holdings Inc. | finance | 12 |
| ONMD | OneMedNet Corp | health-care | 6 |
| OKE | ONEOK Inc. | utilities | 61 |
| OSPN | OneSpan Inc. | technology | 31 |
| OSW | OneSpaWorld Holdings Limited | consumer-discretionary | 28 |
| ONEW | OneWater Marine Inc. | consumer-discretionary | 6 |
| ONFO | Onfolio Holdings Inc. | technology | 2 |
| ONIT | Onity Group Inc. | finance | 0 |
| OKUR | OnKure Therapeutics Inc. | health-care | 8 |
| ONTO | Onto Innovation Inc. | industrials | 3 |
| OOMA | Ooma Inc. | technology | 15 |
| OPBK | OP Bancorp | finance | 0 |
| OPAL | OPAL Fuels Inc. | utilities | 0 |
| LPRO | Open Lending Corporation | finance | 7 |
| OTEX | Open Text Corporation | technology | 13 |
| OPEN | Opendoor Technologies Inc | finance | 9 |
| OPRA | Opera Limited | technology | 8 |
| OPK | OPKO Health Inc. | health-care | 0 |
| OPRT | Oportun Financial Corporation | finance | 63 |
| OPY | Oppenheimer Holdings Inc. | finance | 5 |
| OPFI | OppFi Inc. | finance | 2 |
| OPXS | Optex Systems Holdings Inc. | technology | 0 |
| OCC | Optical Cable Corporation | industrials | 10 |
| OPRX | OptimizeRx Corporation | consumer-discretionary | 0 |
| OPHC | OptimumBank Holdings Inc. | finance | 1 |
| OPCH | Option Care Health Inc. | health-care | 1 |
| IRD | Opus Genetics Inc. | health-care | 0 |
| ORCL | Oracle Corporation | technology | 9 |
| OGEN | Oragenics Inc. | health-care | 4 |
| ORMP | Oramed Pharmaceuticals Inc. | health-care | 3 |
| OBT | Orange County Bancorp Inc. | finance | 6 |
| ORKT | Orangekloud Technology Inc. | technology | 13 |
| OSUR | OraSure Technologies Inc. | health-care | 0 |
| OBIO | Orchestra BioMed Holdings Inc. | health-care | 46 |
| ORC | Orchid Island Capital Inc. | real-estate | 0 |
| OGI | Organigram Holdings Inc. | health-care | 22 |
| ORGO | Organogenesis Holdings Inc. | health-care | 0 |
| OGN | Organon & Co. | health-care | 48 |
| ORIC | Oric Pharmaceuticals Inc. | health-care | 12 |
| OCG | Oriental Culture Holding LTD | consumer-discretionary | 6 |
| ORIS | Oriental Rise Holdings Limited | consumer-staples | 2 |
| SEED | Origin Agritech Limited | consumer-staples | 6 |
| OBK | Origin Bancorp Inc. | finance | 2 |
| ORGN | Origin Materials Inc. | industrials | 25 |
| OESX | Orion Energy Systems Inc. | consumer-discretionary | 0 |
| ORN | Orion Group Holdings Inc. | industrials | 0 |
| ONL | Orion Office REIT Inc. | real-estate | 41 |
| OEC | Orion S.A. | industrials | 12 |
| IX | Orix Corp | finance | 46 |
| ORA | Ormat Technologies Inc. | utilities | 15 |
| ORRF | Orrstown Financial Services Inc. | finance | 6 |
| OFIX | Orthofix Medical Inc. | health-care | 60 |
| ORKA | Oruka Therapeutics Inc. | health-care | 18 |
| OSTX | OS Therapies Incorporated | health-care | 5 |
| OSCR | Oscar Health Inc. | health-care | 14 |
| OSIS | OSI Systems Inc. | technology | 3 |
| OR | Osisko Gold Royalties Ltd | basic-materials | 1 |
| OST | Ostin Technology Group Co. Ltd. | technology | 10 |
| OTIS | Otis Worldwide Corporation | technology | 1 |
| OTTR | Otter Tail Corporation | utilities | 44 |
| OUST | Ouster Inc. | industrials | 8 |
| OUT | OUTFRONT Media Inc. | real-estate | 45 |
| OTLK | Outlook Therapeutics Inc. | health-care | 0 |
| OM | Outset Medical Inc. | health-care | 47 |
| OVID | Ovid Therapeutics Inc. | health-care | 9 |
| OVV | Ovintiv Inc. | energy | 13 |
| OC | Owens Corning Inc | industrials | 29 |
| OWLT | Owlet Inc. | industrials | 0 |
| OXBR | Oxbridge Re Holdings Limited | finance | 4 |
| OXM | Oxford Industries Inc. | consumer-discretionary | 6 |
| OXLC | Oxford Lane Capital Corp. | finance | 21 |
| OXSQ | Oxford Square Capital Corp. | finance | 0 |