| 1 | M & R Exploration Company | Houston, TX 77074 | Oil & Gas Operator | Aug 2003 |
| 2 | M-G Gas Company, Inc. | Plano, TX 75086 | Oil & Gas Operator | Jun 1999 |
| 3 | M. E. Operating & Services, Inc. | Fort Worth, TX 76104 | Oil & Gas Operator | Feb 2026 |
| 4 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 5 | Magnolia Oil & Gas Operating LLC | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |
| 6 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 7 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Feb 2026 |
| 8 | Main Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2009 |
| 9 | Mantle Oil & Gas, LLC | Friendswood, TX 77546 | Oil & Gas Operator | Feb 2026 |
| 10 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Dec 2025 |
| 11 | Market Street Energy, Inc. | Flatonia, TX 78941 | Oil & Gas Operator | Feb 2026 |
| 12 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Feb 2026 |
| 13 | Marshall, Sam | Granbury, TX 76048 | Oil & Gas Operator | Aug 2010 |
| 14 | Marshall, Samuel Meek, Estate Of | Granbury, TX 76048 | Oil & Gas Operator | Feb 2026 |
| 15 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Feb 2026 |
| 16 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 17 | Mascot Oil Company | Schulenburg, TX 78956 | Oil & Gas Operator | Feb 2026 |
| 18 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 19 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 20 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 21 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 22 | MB Energy, LLC | San Antonio, TX 78233 | Oil & Gas Operator | Feb 2026 |
| 23 | McCord Production, LTD. | Houston, TX 77002 | Gas Operator | Feb 1997 |
| 24 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 25 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 26 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 27 | Meridian Oil Production Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 2024 |
| 28 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Feb 2026 |
| 29 | Messy Oil And Gas, LLC | Garwood, TX 77442 | Oil & Gas Operator | Feb 2026 |
| 30 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 31 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 32 | Mid Texas Natural Gas | Kyle, TX 78640 | Oil & Gas Operator | May 2019 |
| 33 | Middleton Oil Company | Houston, TX 77006 | Oil & Gas Operator | Feb 2026 |
| 34 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 35 | Midstates Corporation | San Antonio, TX 78217 | Oil & Gas Operator | Feb 2026 |
| 36 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 37 | Millennium Exploration Co. LLC | San Antonio, TX 78232 | Oil & Gas Operator | Feb 2026 |
| 38 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 39 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 40 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 41 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 2007 |
| 42 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Feb 2026 |
| 43 | Modern Exploration, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Feb 2026 |
| 44 | Mohican Oil & Gas, L.L.C. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Apr 2013 |
| 45 | Mohican Operating, L.L.C. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2021 |
| 46 | Monitor O&G, L.L.C. | Frisco, TX 75034 | Oil & Gas Operator | Jan 2016 |
| 47 | Mosaic Oil LLC | Dallas, TX 75205 | Oil & Gas Operator | Feb 2026 |
| 48 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 49 | Mowata Oil Company | Victoria, TX 77903 | Oil & Gas Operator | Oct 1996 |
| 50 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 51 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Dec 2025 |