| Abbreviation | Definition |
|---|---|
| MPET | Magellan Petroleum Corporation |
| MPLX | Mediaplex, Inc. |
| MPML | M P M Technologies, Inc. |
| MPOR | Mighty Power U S A, Inc. |
| MPPP | MP3.Com, Inc. |
| MPRSD | Microprose, Inc. |
| MPRWL | Mississippi Power Company |
| MPRWP | Mississippi Power Company Preferred |
| MPSI | M P S I Systems, Inc. |
| MPSS | MPEG Super Site |
| MPTG | Masterpiece Technology Group |
| MPTV | M P T V, Inc. |
| MPVI | Mountain Province Mining, Inc. |
| MPWG | M P W Industrial Service Group, Inc. |
| MPWR | M G C Communications, Inc. |
| MPWRP | M G C Communications, Inc. Preferred |
| MQST | MapQuest.Com, Inc. (delisted) |
| MRAE | Mirae Corporation |
| MRAY | Murray United Development Corporation |
| MRBA | Marimba, Inc. |