| 1 | Maersk Energy Inc. | Houston, TX 77042 | Oil & Gas Operator | Oct 1994 |
| 2 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 3 | Marmaton Oil Company | Houston, TX 77002 | Oil & Gas Operator | Jul 1998 |
| 4 | McGehee, George T. Operating Co. | Houston, TX 77024 | Oil & Gas Operator | Oct 1997 |
| 5 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 6 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Apr 2026 |
| 7 | Medallion Petroleum, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2015 |
| 8 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 9 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Apr 2026 |
| 10 | MFP Petroleum LP | Oklahoma City, OK 73142-3017 | Gas Operator | Jan 2026 |
| 11 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2026 |
| 12 | Mineral Technologies, Inc. | Midland, TX 79704 | Oil & Gas Operator | Apr 2026 |
| 13 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Apr 2026 |
| 14 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 15 | Murphy Exploration & Prod. Co. | Houston, TX 77094 | Oil & Gas Operator | Jun 2011 |
| 16 | Murphy Oil USA, Inc. | New Orleans, LA 70161 | Oil & Gas Operator | Jan 1993 |