| ORLY | O'Reilly Automotive, Inc. | Consumer Cyclical | $71.5B | — | 0 |
| OVLY | Oak Valley Bancorp | Financial Services | $286M | — | 0 |
| OAKV | Oak View Bankshares, Inc. | Financial Services | $66.6M | — | 0 |
| OACCW | Oaktree Acquisition Corp. III Life Sciences | Financial Services | $239M | — | 0 |
| OCSL | Oaktree Specialty Lending Corporation | Financial Services | $1.1B | — | 0 |
| OAKC | Oakworth Capital, Inc. | — | — | — | 0 |
| OTLY | Oatly Group AB | Consumer Defensive | $379M | — | 0 |
| OBIBF | OBIC Business Consultants Co., Ltd./ADR | — | — | — | 0 |
| OBIIF | OBIC Co.,Ltd. | Technology | $13.6B | — | 0 |
| OWLS | OBOOK Holdings Inc. | Technology | $451M | — | 0 |
| OBE | Obsidian Energy Ltd. | Energy | $751M | — | 0 |
| OBX | Obsidian Therapeutics Inc. | — | — | — | 0 |
| OXY-WT | Occidental Petroleum Corporation | Energy | $59.1B | — | 0 |
| OCEA | Ocean Biomedical, Inc. | Healthcare | $0.5M | — | 0 |
| OCAC-RI | Ocean Capital Acquisition Corporation | — | — | — | 0 |
| OPTT | Ocean Power Technologies, Inc. | Industrials | $13.7M | — | 0 |
| CPWR | Ocean Thermal Energy Corporation | Utilities | $0.8M | — | 0 |
| OGC | OceanaGold Corporation | Basic Materials | $6.2B | — | 0 |
| OII | Oceaneering International, Inc. | Energy | $4.6B | — | 0 |
| OCFC | OceanFirst Financial Corp. | Financial Services | $1.0B | — | 0 |
| OHACR | Oceanhawk Acquisition Corp. | — | — | — | 0 |
| OHII | Oceanhawk Acquisition II Corp. | — | — | — | 0 |
| FEOVF | Oceanic Iron Ore Corp. | Basic Materials | $141M | — | 0 |
| OCLTU | OceanLight Acquisition Corporation | — | — | — | 0 |
| OP | OceanPal Inc. | Industrials | $187M | — | 0 |