| Liberty Mutual Group | Boston | 1912 |
| Litton Industries | Milwaukee | 1953 |
| LJN Toys | Nova Iorque | 1967 |
| Logitech | Lausana, Newark | 2 de outubro de 1981 |
| Lonely Planet | Melbourne | 1972 |
| Long Island Rail Road | Jamaica | 1834 |
| Lord & Taylor | Nova Iorque | 1826 |
| Lotus Software | Cambridge | 1982 |
| M-Audio | Cumberland | 1998 |
| Mack Trucks | Allentown, Greensboro | 1900 |
| Macromedia | São Francisco | 25 de fevereiro de 1992 |
| Mad Catz | San Diego | 1989 |
| Magpul Industries | — | — |
| Major League Soccer | Pennsylvania Plaza | 17 de dezembro de 1993 |
| Malpaso Productions | Burbank | 1967 |
| Malwarebytes | Santa Clara | 21 de janeiro de 2008 |
| Manpower | Milwaukee | 1948 |
| Marathon Oil | Houston | 1887 |
| Marmot | Santa Rosa | 1974 |
| Martin Marietta | Bethesda | 1961 |
| Marvell Technology | Santa Clara | 1995 |
| Masdar | Abu Dhabi | abril 2006 |
| Massachusetts Mutual Life Insurance Company | Springfield | 1851 |
| Massey Ferguson | Duluth | 1953 |
| Masten Space Systems | Mojave | 2004 |
| MasterClass | São Francisco | 2015 |
| Match Group | Kerrville | 2009 |
| Matson, Inc. | Honolulu | 1882 |
| Mattel | El Segundo | janeiro 1945 |
| Maxwell Technologies | San Diego | 1965 |
| McIntosh Laboratory | Binghamton, Nova Iorque | 1949 |
| McKesson Corporation | Irving | 1994 |
| Meade Instruments | Irvine | 1972 |
| Menards | Eau Claire | 1962 |
| Mercer Automobile Company | New Britain | 1909 |
| Mercury Marine | Fond du Lac | 1939 |
| Merrell | Rockford | 1981 |
| Merrill Lynch | Nova Iorque | 6 de janeiro de 1914 |
| MetLife | Nova Iorque | 24 de março de 1868 |
| Metro-Goldwyn-Mayer | Los Angeles | 17 de abril de 1924 |
| MGM Holdings | Beverly Hills | 11 de fevereiro de 2005 |
| Micro Instrumentation and Telemetry Systems | Albuquerque | 1970 |
| Micron Technology | Boise | outubro 1978 |
| Middle-earth Enterprises | Berkeley | 2022 |
| MIPS Technologies | Sunnyvale | 1984 |
| Missouri Pacific Railroad | St. Louis | 1917 |
| MITRE Corporation | Bedford | 1958 |
| Moderna Therapeutics | Cambridge | 2010 |