| 1 | M A S Operators | Kilgore, TX 75663 | Oil & Gas Operator | Jul 1999 |
| 2 | M. E. Operating & Services, Inc. | Fort Worth, TX 76104 | Oil & Gas Operator | Oct 2025 |
| 3 | M. Grace, Inc. | Henderson, TX 75653 | Oil & Gas Operator | Oct 2025 |
| 4 | Machin & Associates, Inc. | Longview, TX 75606 | Oil & Gas Operator | Oct 2025 |
| 5 | Magna Oil & Gas Corporation | Irving, TX 75017 | Oil & Gas Operator | Feb 2016 |
| 6 | Manziel Management Corporation | Tyler, TX 75711 | Oil Operator | Feb 2014 |
| 7 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 8 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 9 | McBay Company | Grapeland, TX 75844 | Oil & Gas Operator | Feb 2002 |
| 10 | McBee Company, The | Dallas, TX 75219 | Oil & Gas Operator | Dec 1997 |
| 11 | McBride, Jerrel L Enterprise Inc | Kilgore, TX 75663 | Oil & Gas Operator | Jun 1999 |
| 12 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Oct 2025 |
| 13 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 14 | Means Oil Co. | Corsicana, TX 75110 | Oil & Gas Operator | Feb 2013 |
| 15 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 16 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 17 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 18 | Miller Production Co. | Tyler, TX 75701 | Oil & Gas Operator | Oct 2025 |
| 19 | Miller, Mike / Miller Prod. Co. | Corsicana, TX 75110 | Oil & Gas Operator | Oct 2025 |
| 20 | MLB Operating Services, LLC | Tenn Colony, TX 75861 | Oil & Gas Operator | Oct 2025 |
| 21 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 22 | Monsanto Company | Indianapolis, IN 46280 | Oil & Gas Operator | Jan 2005 |
| 23 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 24 | Mud Creek Operating, LLC | Tyler, TX 75702 | Oil & Gas Operator | Oct 2025 |
| 25 | Mueller Exploration, Inc. | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 26 | Mustang Drilling, Inc. | Henderson, TX 75653 | Oil & Gas Operator | Aug 2024 |