- MatrixCare
- Maxwell Group
- Maybrook Holdings
- Mayflower Retirement Community
- MB Financial Bank
- MBET Health
- McBee
- McDonnell Construction
- McGuire Group
- McGuireWoods
- McKinsey & Co.
- MCS Plan
- MDA Capital Group
- MDS Consultant LLC
- Meadowbrook Post-Acute
- MED Healthcare Partners
- MedaSync
- MedCity News
- Médecins Sans Frontières
- MedEquities