| MPMagga Products Company INC | Holly Hill | FL | — | ◇ UNVERIFIED |
| MCMaggie Chacon | El Paso | TX | — | ◇ UNVERIFIED |
| MIMagma INC | Lakewood | CA | — | ◇ UNVERIFIED |
| MSMagni-fab Southwest Company, INC. | Howe | TX | — | ◇ UNVERIFIED |
| MMMagnuson Metals Utah, LLC | Salt Lake City | UT | — | ◇ UNVERIFIED |
| MSMain Street Fabrications and Manufacturing, LLC | Brooksville | FL | — | ◇ UNVERIFIED |
| MMMaintenance & Machinery Erectors, INC. | Mulberry | FL | — | ◇ UNVERIFIED |
| MWMajestic Water Spouts, LLC | Mesa | AZ | — | ◇ UNVERIFIED |
| MSManitex Sabre INC | Knox | IN | — | ◇ UNVERIFIED |
| MFMann's Fabrication & Welding Inc. | Columbus | OH | — | ◇ UNVERIFIED |
| MGManpower Group | Amarillo | TX | — | ◇ UNVERIFIED |
| MMMansfield Metal Solutions LLC | Ontario | CA | — | ◇ UNVERIFIED |
| MIManufab, INC. | Bay Saint Louis | MS | — | ◇ UNVERIFIED |
| MWManz Work, INC. | Orlando | FL | — | ◇ UNVERIFIED |
| MAMarine Accessories Corporation (mac) | Maryville | TN | — | ◇ UNVERIFIED |
| MFMarine Fab & Repair, INC | Houma | LA | — | ◇ UNVERIFIED |
| MIMaritime International INC | Broussard | LA | — | ◇ UNVERIFIED |
| MBMark Bailey | Irwindale | CA | — | ◇ UNVERIFIED |
| MBMark Body Truck & Equipment CO | Imlay City | MI | — | ◇ UNVERIFIED |
| MGMark Godfrey Sr Individual Dba United Iron Works | Orland | CA | — | ◇ UNVERIFIED |
| MMMarkle Manufacturing Company of San Antonio | San Antonio | TX | — | ◇ UNVERIFIED |
| MMMarks Metal Technology INC | Clackamas | OR | — | ◇ UNVERIFIED |
| MSMark Steel CORP | Salt Lake City | UT | — | ◇ UNVERIFIED |
| MLMarrick LLC | Norfolk | VA | — | ◇ UNVERIFIED |
| MSMarshall Steel Services INC. | Arvada | CO | — | ◇ UNVERIFIED |
| MMMartelli's Metal Fabrication INC | Ivyland | PA | — | ◇ UNVERIFIED |
| MSMartha S Materials INC | Lexington | KY | — | ◇ UNVERIFIED |
| MSMartinez Steel | San Francisco | CA | — | ◇ UNVERIFIED |
| MIMartin Iron Works, INC | Reno | NV | — | ◇ UNVERIFIED |
| MIMartin Iron Works, INC. | Reno | NV | — | ◇ UNVERIFIED |
| MMMartin Manufactuirng, INC. | Sapulpa | OK | — | ◇ UNVERIFIED |
| MHMartin-Pittman Holdings, Inc. | Indianapolis | IN | — | ◇ UNVERIFIED |
| MSMartin Steel Constructors | Eleele | HI | — | ◇ UNVERIFIED |
| MSMartin Steel INC | Huntington | WV | — | ◇ UNVERIFIED |
| MSMaryland Structural Fabricators INC | Millington | MD | — | ◇ UNVERIFIED |
| MLMascoat LLC | West Monroe | LA | — | ◇ UNVERIFIED |
| MFMas Fab, Incorporated Dba Formit Steel Company | Red Lion | PA | — | ◇ UNVERIFIED |
| MSMason Structural Steel INC. | Walton Hills | OH | — | ◇ UNVERIFIED |
| MWMason West, INC | Placentia | CA | — | ◇ UNVERIFIED |
| MWMaspeth Welding, INC | New York | NY | — | ◇ UNVERIFIED |
| MMMass Machine & Fabricating Company | Washington | PA | — | ◇ UNVERIFIED |
| MMMatcor Metal Fabrication | Morton | IL | — | ◇ UNVERIFIED |
| MCMaterial Control Systems, INC. | Cordova | IL | — | ◇ UNVERIFIED |
| MHMaterial Handling Technologies, INC. | North Syracuse | NY | — | ◇ UNVERIFIED |
| MIMattessich Iron, LLC | Baldwinsville | NY | — | ◇ UNVERIFIED |
| MIMattessich Iron, LLC | Memphis | NY | — | ◇ UNVERIFIED |
| MBMaura Buildings, Incorporated | Lebanon | PA | — | ◇ UNVERIFIED |
| MMMaurice Mesple Dba Mesples Machine Shop and Pump | Fresno | CA | — | ◇ UNVERIFIED |
 Maverick Aerospace #2 | Santa Fe Springs | CA | — | ◇ UNVERIFIED |
| MSMay Specialty Fabricators, INC. | Register | GA | — | ◇ UNVERIFIED |
