| Massachusetts Institute of Technology Department of Mathematics | Massachusetts |
| Massachusetts Institute of Technology Digital Currency Initiative | Massachusetts |
| Massachusetts Institute of Technology Electrical Engineering & Computer Science Department | Massachusetts |
| Massachusetts Institute of Technology Engineering Quantum Systems | Massachusetts |
| Massachusetts Institute of Technology Global Startup Labs | Massachusetts |
| Massachusetts Institute of Technology Hacking Medicine | Massachusetts |
| Massachusetts Institute of Technology Interdisciplinary Quantum Information Science and Engineering | Massachusetts |
| Massachusetts Institute of Technology Lincoln Laboratory | Massachusetts |
| Massachusetts Institute of Technology Media Lab | Massachusetts |
| Massachusetts Institute of Technology Microsystems Technology Laboratories | Massachusetts |
| Massachusetts Institute of Technology OpenCourseWare | Massachusetts |
| Massachusetts Institute of Technology Sloan School of Management | Massachusetts |
| Massachusetts Institute of Technology Software Agents Group | Massachusetts |
| Massachusetts Institute of Technology xPRO Quantum Computing Fundamentals | Massachusetts |
| Massachusetts Technology Collaborative | Massachusetts |
| Massachusetts Technology Corporation | Massachusetts |
| Massachusetts Technology Leadership Council, Inc. | Massachusetts |
| Massachussetts College of Pharmacy and Health Sciences | Massachusetts |
| Massar Capital Management, L.P. | |
| MassBlurb | |
| Massbridge Software | |
| MassChallenge, Inc. | Massachusetts |
| Massena Savings & Loan | |
| MassInteract | |
| Massive Ant | Florida |
| Massive Bio, Inc. | New York |
| Massive Networks | Colorado |
| Massive Studios | |
| MassLight, Inc. | District of Columbia |
| Massman Automation Designs, LLC | Minnesota |
| MassMatrix, Inc. | Ohio |
| MassMedia | |
| Masson | New York |
| MassRobotics | Massachusetts |
| MassVentures | Massachusetts |
| MAST | Texas |
| MAST Biosurgery | |
| Mast Distributors, Inc. | New York |
| MasTec Network Solutions | Florida |
| Mastech Digital, Inc. | Pennsylvania |
| Mastech InfoTrellis, Inc. | Georgia |
| Mastel Precision Surgical Instruments, Inc. | South Dakota |
| Masten Space Systems | |
| Master & Dynamic | |
| Master List AI | |
| Master Meter, Inc. | |
| Master of Code Global | California |
| Master of Shapes, Inc. | |
| Master Software Corporation | New York |
| Master System, Inc. | California |