| 1 | Magnolia Oil & Gas Operating LLC | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 2 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 2025 |
| 3 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 4 | Mantle Oil & Gas, LLC | Friendswood, TX 77546 | Oil & Gas Operator | Dec 2025 |
| 5 | Marino, Charles B. | Tomball, TX 77377 | Oil & Gas Operator | Dec 2025 |
| 6 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 7 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 8 | Mastodon Operating Company, LLC | Houston, TX 77027 | Oil & Gas Operator | Dec 2025 |
| 9 | Maverick Prod. Co., Inc. | Houston, TX 77056 | Oil & Gas Operator | Dec 2025 |
| 10 | McCarter, A. Nelson | Houston, TX 77063 | Oil & Gas Operator | Aug 2003 |
| 11 | McCarthy Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Oct 2007 |
| 12 | McGowan Working Partners | Jackson, MS 39296 | Oil & Gas Operator | Dec 2000 |
| 13 | McGowan Working Partners, Inc. | Jackson, MS 39296 | Oil & Gas Operator | Dec 2025 |
| 14 | McKenzie Production Company | Houston, TX 77063 | Oil & Gas Operator | May 1995 |
| 15 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 16 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 17 | Mercantile Oil & Gas Prod. Corp. | Galena Park, TX 77547 | Oil & Gas Operator | Jun 2016 |
| 18 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | Oct 2025 |
| 19 | Metano Energy, LP | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2008 |
| 20 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 21 | Miller, W. C. Operating Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2025 |
| 22 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 23 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 24 | Mobpar, Inc. | Houston, TX 77219 | Oil & Gas Operator | Dec 2025 |
| 25 | Mojac Energy Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1997 |
| 26 | MSR Exploration, Inc. | Winters, TX 79567 | Oil & Gas Operator | Mar 2000 |
| 27 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | Aug 2020 |
| 28 | Mustang Energy Inc. | Porter, TX 77365 | Oil & Gas Operator | Mar 2008 |