| M | | Retail-Department Stores | 794367 |
| MA | | Services-Business Services, NEC | 1141391 |
| MAA | | Real Estate Investment Trusts | 912595 |
| MAAS | | Investment Advice | 1750264 |
| MAC | | Real Estate Investment Trusts | 912242 |
| MACI | | Services-Business Services, NEC | 2016221 |
| MADL | | Commodity Contracts Brokers & Dealers | 1052354 |
| MAGE | | Metal Mining | 1515317 |
| MAGH | | Electrical Work | 2046117 |
| MAGN | | Paper Mills | 41719 |
| MAIA | | Pharmaceutical Preparations | 1878313 |
| MAIN | | - | 1396440 |
| MAJI | | Communications Services, NEC | 1492448 |
| MALG | | Beverages | 1309251 |
| MAMA | | Sausages & Other Prepared Meat Products | 1520358 |
| MAMK | | Miscellaneous Fabricated Textile Products | 2008007 |
| MAMO | | Miscellaneous Transportation Equipment | 1952853 |
| MAN | | Services-Help Supply Services | 871763 |
| MANA | | - | 1852023 |
| MANH | | Services-Prepackaged Software | 1056696 |
| MANU | | Services-Amusement & Recreation Services | 1549107 |
| MAPPF | | - | 1493130 |
| MAPS | | Services-Prepackaged Software | 1779474 |
| MAR | | Hotels & Motels | 1048286 |
| MARA | | Finance Services | 1507605 |
| MARPS | | Oil Royalty Traders | 62362 |
| MAS | | Heating Equip, Except Elec & Warm Air; & Plumbing Fixtures | 62996 |
| MASI | | Electromedical & Electrotherapeutic Apparatus | 937556 |
| MASK | | Services-Computer Programming Services | 1993097 |
| MASS | | Measuring & Controlling Devices, NEC | 1555279 |
| MAT | | Dolls & Stuffed Toys | 63276 |
| MATH | | Finance Services | 1682241 |
| MATV | | Paper Mills | 1000623 |
| MATW | | Nonferrous Foundries (Castings) | 63296 |
| MATX | | Water Transportation | 3453 |
| MAX | | Services-Business Services, NEC | 1818383 |
| MAXN | | Semiconductors & Related Devices | 1796898 |
| MAYS | | Opeators of Nonresidential Buildings | 54187 |
| MAZE | | Biological Products, (No Diagnostic Substances) | 1842295 |
| MB | | Retail-Eating Places | 2027265 |
| MBAI | | X-Ray Apparatus & Tubes & Related Irradiation Apparatus | 1610590 |
| MBAV | | Blank Checks | 2016072 |
| MBBC | | Savings Institutions, Not Federally Chartered | 1835385 |
| MBC | | Wood Household Furniture, (No Upholstered) | 1941365 |
| MBCN | | State Commercial Banks | 836147 |
| MBI | | Surety Insurance | 814585 |
| MBIN | | State Commercial Banks | 1629019 |
| MBIO | | Pharmaceutical Preparations | 1680048 |
| MBLY | | Services-Prepackaged Software | 1910139 |
| MBOT | | Surgical & Medical Instruments & Apparatus | 883975 |
