| 1 | M & K Oil Company LLC | Gillette, WY 82716 | Oil & Gas Operator | Jan 2026 |
| 2 | M & K Oil Operations | | Oil & Gas Operator | Sep 1994 |
| 3 | M-3 Industries | Casper, WY 82602 | Oil & Gas Operator | Dec 2025 |
| 4 | Mack Energy Corporation | Artesia, NM 88211 | Oil & Gas Operator | Jan 2026 |
| 5 | Main Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2009 |
| 6 | Manx Oil Corporation | Casper, WY 82601 | Oil & Gas Operator | Jun 2010 |
| 7 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Jan 2026 |
| 8 | Marmik Oil Company | El Dorado, AR 71730 | Oil & Gas Operator | Jan 2015 |
| 9 | Marquis-Allred Eng Inc | | Oil & Gas Operator | Apr 1992 |
| 10 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Dec 2025 |
| 11 | Maxim Drilling & Expl Inc | Gillette, WY 82717 | Oil & Gas Operator | Jan 2026 |
| 12 | Mbi Oil & Gas LLC | Dickinson, ND 58601 | Oil & Gas Operator | Jan 2026 |
| 13 | McCulliss Resource Company Inc | Denver, CO 80202 | Oil & Gas Operator | Jun 1999 |
| 14 | McMurry Energy Company | | Oil & Gas Operator | Dec 2001 |
| 15 | McMurry Oil LLC | Denver, CO 80202 | Oil & Gas Operator | Dec 2004 |
| 16 | McO Resources Corporation | | Oil & Gas Operator | Feb 1986 |
| 17 | McQueen Ed & Company Inc | Lindsey, OK 73052 | Oil & Gas Operator | Apr 2014 |
| 18 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 19 | MDS Energy Development LLC | | Oil & Gas Operator | Jan 2026 |
| 20 | Medallion Exploration | Holladay, UT 84117 | Oil & Gas Operator | Dec 2015 |
| 21 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 22 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Mar 2026 |
| 23 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | Jan 2026 |
| 24 | Methane Productions Inc | Recluse, WY 82725 | Oil & Gas Operator | Apr 2007 |
| 25 | Michigan-Wisconsin Pipe Line Co | | Oil & Gas Operator | Dec 1983 |
| 26 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2026 |
| 27 | Midgard Energy Company | The Woodlands, TX 77380 | Oil & Gas Operator | Dec 2014 |
| 28 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 29 | Mobil Expl & Producing North America Inc | | Oil & Gas Operator | Nov 1986 |
| 30 | Mon-Oil Inc | | Oil & Gas Operator | Apr 1996 |
| 31 | Moncrief W A Jr | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2026 |
| 32 | Montex Drilling Company LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2026 |
| 33 | Morgan Energy Corporation | Englewood, CO 80110 | Oil & Gas Operator | Mar 2006 |
| 34 | Mustang Oil & Gas Corporation | Wichita Falls, TX 76308 | Oil & Gas Operator | Jul 2021 |
| 35 | MWJ Producing Company | Midland, TX 79701 | Oil & Gas Operator | Jul 1998 |