| 1 | Mack Energy Co. | Duncan, OK 73534 | Oil & Gas Operator | Oct 2024 |
| 2 | Mahfouz Energy Company | Houston, TX 77255 | Oil & Gas Operator | Nov 2020 |
| 3 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Dec 2024 |
| 4 | Marathon Oil Company | Houston, TX 77024 | Oil & Gas Operator | Oct 2024 |
| 5 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2024 |
| 6 | Maverick Energy & Dev. Corp. | Austin, TX 78746 | Oil & Gas Operator | Dec 2024 |
| 7 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2024 |
| 8 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 9 | Mayne & Mertz, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2013 |
| 10 | McBay Company | Grapeland, TX 75844 | Oil & Gas Operator | Feb 2002 |
| 11 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Dec 2024 |
| 12 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 13 | Means Oil Co. | Corsicana, TX 75110 | Oil & Gas Operator | Feb 2013 |
| 14 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 15 | Mid-Gulf, Inc. | Brenham, TX 77834 | Oil & Gas Operator | Mar 2008 |
| 16 | Midcoast G & P (East Texas) L.P. | Houston, TX 77002 | Oil & Gas Operator | Dec 2024 |
| 17 | Miller Energy Inc | Houston, TX 77024 | Oil & Gas Operator | Oct 2016 |
| 18 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 19 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 20 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2024 |
| 21 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 22 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 23 | Mud Creek Operating, LLC | Tyler, TX 75702 | Oil & Gas Operator | Dec 2024 |
| 24 | Mustang Drilling, Inc. | Henderson, TX 75653 | Oil & Gas Operator | Aug 2024 |
| 25 | Mustang Drilling, LTD. | Henderson, TX 75653 | Oil & Gas Operator | May 2008 |