| 1 | M-C Production & Drilling Co,Inc | Longview, TX 75608 | Oil & Gas Operator | Oct 2025 |
| 2 | M-Five Oil Company | Seguin, TX 78155 | Oil & Gas Operator | Apr 2002 |
| 3 | Main Street Royalty, Inc. | Lockhart, TX 78644 | Oil & Gas Operator | Aug 1999 |
| 4 | Malone Oil Production | La Vernia, TX 78121 | Oil & Gas Operator | Oct 2025 |
| 5 | Marymac Oil Company | Lockhart, TX 78644 | Oil & Gas Operator | Sep 2001 |
| 6 | Matrix Producing Company | Luling, TX 78648 | Oil & Gas Operator | Feb 2005 |
| 7 | Maverick Prod. Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 8 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 9 | McLain Exploration, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Mar 2008 |
| 10 | McMullan Oil Company | San Antonio, TX 78212 | Oil & Gas Operator | Jun 2023 |
| 11 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 12 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 13 | Metco Oil Corporation | Seguin, TX 78155 | Oil Operator | Apr 2016 |
| 14 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 15 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 16 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 17 | Mobile Production Systems, Inc. | Austin, TX 78711 | Oil & Gas Operator | Feb 1995 |
| 18 | Mockingbird Oil, Inc. (I) | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 19 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 20 | Multipay Energy, Inc. | Austin, TX 78749 | Oil Operator | Oct 2025 |
| 21 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Jun 2025 |
| 22 | Muroz International Group Inc | Houston, TX 77056 | Oil Operator | Oct 2025 |