| 1 | Mac Mar Inc | Blairsville, PA 15717-7646 | Oil & Gas Operator | Dec 2025 |
| 2 | MDS Energy Dev LLC | Kittanning, PA 16201-4403 | Oil & Gas Operator | Dec 2025 |
| 3 | Meridian Oil & Gas Enterprises Inc | Blairsville, PA 15717-0337 | Oil & Gas Operator | Dec 2003 |
| 4 | Mid East Oil Co | Indiana, PA 15701-5378 | Gas Operator | Dec 2006 |
| 5 | Mid-Penn Energy Corporation | Harrisburg, PA 17101-1002 | Gas Operator | Dec 2021 |
| 6 | Mieka LLC | Flower Mound, TX 75028-7446 | Oil & Gas Operator | Dec 2014 |
| 7 | Monona LLC | Ligonier, PA 15658-0612 | Gas Operator | Dec 2025 |
| 8 | MTN V Oil & Gas Inc | Indiana, PA 15701-8914 | Oil & Gas Operator | Dec 2025 |
| 9 | Murphy Prod Inc | Vanderbilt, PA 15486-1001 | Oil & Gas Operator | Dec 2025 |