| 1 | M. P. S. Prod. Co. | Houston, TX 77225 | Oil & Gas Operator | Dec 1996 |
| 2 | M.B. Properties, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Oct 1995 |
| 3 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 4 | Marathon Oil Company | Houston, TX 77024 | Oil & Gas Operator | Mar 2024 |
| 5 | Martineau Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | May 2024 |
| 6 | McBee Operating Company, L.L.C. | Dallas, TX 75209 | Oil & Gas Operator | May 2024 |
| 7 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | May 2024 |
| 8 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 9 | MD America Energy, LLC | Houston, TX 77224 | Oil & Gas Operator | Apr 2022 |
| 10 | Medallion Petroleum, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2015 |
| 11 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 12 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | May 2024 |
| 13 | Midcoast G & P (East Texas) L.P. | Houston, TX 77002 | Oil & Gas Operator | May 2024 |
| 14 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 15 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 16 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 17 | Momentum Operating Co., Inc. | Albany, TX 76430 | Oil & Gas Operator | May 2024 |
| 18 | Moon Operating, Inc. | Longview, TX 75601 | Oil & Gas Operator | Mar 2003 |
| 19 | Murphy, K. P. Oil Operator | Kilgore, TX 75663 | Oil & Gas Operator | May 2024 |