| 1 | Magna Oil & Gas Corporation | Irving, TX 75017 | Oil & Gas Operator | Feb 2016 |
| 2 | Magnolia Oil & Gas Operating LLC | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 3 | Magnum Oilfield Services LLC | Bakersfield, CA 93309 | Oil Operator | Oct 2025 |
| 4 | Main Street Royalty, Inc. | Lockhart, TX 78644 | Oil & Gas Operator | Aug 1999 |
| 5 | Marymac Oil Company | Lockhart, TX 78644 | Oil & Gas Operator | Sep 2001 |
| 6 | Maxwell Oil & Gas Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2001 |
| 7 | McA Petroleum Corporation | Flatonia, TX 78941 | Oil & Gas Operator | Oct 2025 |
| 8 | McQueen Ed & Company Inc | Lindsey, OK 73052 | Oil & Gas Operator | Apr 2014 |
| 9 | Meb, LLC | Austin, TX 78737 | Oil Operator | Oct 2025 |
| 10 | Melton, Joe, DRLG. Co., Inc. | Midland, TX 79704 | Oil & Gas Operator | Dec 2004 |
| 11 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 12 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 13 | Mobile Production Systems, Inc. | Austin, TX 78711 | Oil & Gas Operator | Feb 1995 |
| 14 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Oct 2025 |
| 15 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 16 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 17 | Multipay Energy, Inc. | Austin, TX 78749 | Oil Operator | Oct 2025 |
| 18 | Muroz International Group Inc | Houston, TX 77056 | Oil Operator | Oct 2025 |