| 1 | M A S Operators | Kilgore, TX 75663 | Oil & Gas Operator | Jul 1999 |
| 2 | M-C Production & Drilling Co,Inc | Longview, TX 75608 | Oil & Gas Operator | Oct 2025 |
| 3 | Manziel Management Corporation | Tyler, TX 75711 | Oil Operator | Feb 2014 |
| 4 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Aug 2025 |
| 5 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 6 | Matador Production Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 7 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 8 | Mayo, Eddie | Fredericksbrg, TX 78624 | Oil & Gas Operator | Oct 2025 |
| 9 | McBee Company, The | Dallas, TX 75219 | Oil & Gas Operator | Dec 1997 |
| 10 | McBee Operating Company, L.L.C. | Dallas, TX 75209 | Oil & Gas Operator | Oct 2025 |
| 11 | McBrayer Oil Corporation | Rockport, TX 78381 | Oil & Gas Operator | Nov 1994 |
| 12 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Oct 2025 |
| 13 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 14 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 15 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 16 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 17 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 18 | Miken Oil, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 19 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 20 | Mustang Drilling, Inc. | Henderson, TX 75653 | Oil & Gas Operator | Aug 2024 |
| 21 | Mustang Energy Inc. | Porter, TX 77365 | Oil & Gas Operator | Mar 2008 |
| 22 | Mustang Operating Company | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2006 |