- M&T Bank Corporation
- Macerich Company
- Mack Trucks, Inc.
- Mack-Cali Realty Corporation
- Magellan Health Services Incorporated
- Magna Entertainment Corporation
- Mainframe Entertainment Incorporated
- Majestic Athletic
- Major Automotive Companies
- Manor Care Incorporated
- Manpower Incorporated
- Manulife Financial Corporation
- Marine Products Corporation
- Markel Corporation
- Marks & Spencer Limited
- Marriott International Incorporated
- Marsh & McLennan Cos
- Marsh Supermarkets Incorporated
- Marshall & Ilsley Corporation
- Martek Biosciences Corporation
- Martha Stewart Living Omnimedia Incorporated
- Marvel Enterprises Incorporated
- Marvell Technology Group Limited
- Masco Corporation
- Massey Energy Company
- Matrixx Initiatives Incorporated
- Matsushita Electric Industrial Company Limited
- Mattel Inc.
- Maxtor Corporation
- Maytag Corporation
- Mazda Motor Corp.
- MB Financial Incorporated
- MBIA Incorporated
- McAfee Incorporated
- McClatchy Co.
- McCormick & Company Inc.
- McDonald's
- McGraw-Hill Companies Incorporated (The)
- McGraw-Hill Incorporated
- McLeodUSA Incorporated
- MDU Resources Group Incorporated
- Meadow Valley Corporation
- MeadWestvaco Corporation
- Mechanics Bank
- Media General
- Medical Action Industries
- Medifast Incorporated
- MedImmune Incorporated
- Medtronic Incorporated
- Megadata Corporation
- Mellon Financial Corporation
- Men's Wearhouse Incorporated
- Mentor Corporation
- Mercantile Bank Corporation
- Mercantile Bankshares Corporation
- Merck & Company Incorporated
- Mercury General Corporation
- Meredith Corporation
- Meridian Gold Incorporated
- Merrill Lynch & Company Inc.
- Mesa Air Group Incorporated
- Methode Electronics Incorporated
- MetLife Incorporated
- Metro International SA
- Metro-Goldwyn-Mayer Incorporated
- Mexican Restaurants Incorporated
- MGIC Investment Corporation
- MI Developments Incorporated
- Miami Subs Corporation
- Michaels Stores Incorporated
- Michelin Group
- Micron Technology Incorporated
- Microsoft Corp.
- MidAmerican Energy Company
- MidAmerican Energy Holdings Company
- Midway Games Incorporated
- Midwest Air Group Incorporated
- Midwest Banc Holdings Incorporated
- Millennium Pharmaceuticals Incorporated
- Millicom International Cellular SA
- Mills Corporation
- Minnesota Mining & Manufacturing Company
- Mirabilis
- Mirant Corporation
- Misonix Inc.
- Mitsubishi Corporation
- Mitsubishi Electric Corporation
- Mitsubishi Heavy Industries Limited
- Mitsubishi Motors Corp.
- Mitsubishi UFJ Financial Group Incorporated
- Mitsui & Company Limited
- Mittal Steel Company NV
- Mohawk Industries Incorporated
- Molex Incorporated
- Molokai Ranch Limited
- Molson Coors Brewing Company
- Monaco Coach Corporation
- MoneyGram International Incorporated
- Monsanto Company
- Monster Worldwide Incorporated
- MONTPELLIER Group
- Moody's Corporation
- Moog Incorporated
- Morgan Stanley Dean Witter & Company
- Morningstar Incorporated
- Mortgage Assistance
- Morton's Restaurant Group Incorporated
- Mossimo Incorporated
- Motorola, Inc.
- MRV Communications Incorporated
- MSC Industrial Direct
- MSC Industrial Direct Company Incorporated
- Multimedia Games Incorporated
- Murphy Oil Corporation
- Muvico Theaters
- Mylan Laboratories Incorporated
- Myriad Genetics Incorporated
- MySpace