- MACPAC
- Mailman School of Public Health
- Maine Department of Health and Human Services
- Maine Health Care Association
- Maine Veterans’ Home
- Maine Veterans’ Homes
- Mainstreet
- Mainstreet Investments
- Majestic Care
- Managed Medicare
- Management and Network Services
- Manchester Manor Health Care Center
- ManorCare
- Marcum LLP
- Marcus & Millichap
- Margaritaville Holdings
- MarketWatch
- Marquis
- Marquis Companies
- Marquis Health Services
