| 1 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 2 | Majestic Resources, Inc. | Dripping SPGS, TX 78620 | Oil & Gas Operator | Nov 2007 |
| 3 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 4 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Oct 2025 |
| 5 | Marathon Oil Ef LLC | Houston, TX 77252 | Oil & Gas Operator | Oct 2025 |
| 6 | Mark IV Energy | San Antonio, TX 78213 | Oil & Gas Operator | Apr 1993 |
| 7 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 8 | Maverick Energy & Dev. Corp. | Austin, TX 78746 | Oil & Gas Operator | Oct 2025 |
| 9 | McCombs Energy LLC | Houston, TX 77056 | Oil & Gas Operator | Jan 2006 |
| 10 | McGowen Resources Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2003 |
| 11 | McLain Exploration, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Mar 2008 |
| 12 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 13 | Mego Resources, LLC | Taft, TX 78390 | Oil & Gas Operator | Oct 2025 |
| 14 | Merta, Mike | Alice, TX 78333 | Oil & Gas Operator | Aug 2005 |
| 15 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 16 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 17 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 18 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 19 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 20 | Mo-Jon, Inc. | Edroy, TX 78352 | Oil & Gas Operator | May 1999 |
| 21 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 22 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Oct 2025 |
| 23 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Oct 2025 |
| 24 | Morgan Enterprises, Inc. | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 25 | Moy, Gary | Falls City, TX 78113 | Oil & Gas Operator | Nov 1998 |
| 26 | MPG Petroleum | San Antonio, TX 78217 | Oil & Gas Operator | Aug 2003 |
| 27 | MPG Petroleum, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 28 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 29 | Munoco Co. | El Dorado, AR 71730 | Oil & Gas Operator | Jul 2021 |
| 30 | Munson, David M. Inc. | Dallas, TX 75251 | Oil & Gas Operator | Oct 2025 |
| 31 | Murphy Expl. & Prod. Co. - USA | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 32 | Murphy Exploration & Prod. Co. | Houston, TX 77094 | Oil & Gas Operator | Jun 2011 |
| 33 | Murphy Exploration & Production | Houston, TX 77024 | Oil Operator | Jan 2025 |