Complex sentence: Large employers in Maryland include Black & Decker, Legg Mason, Lockheed Martin, Marriott International, McCormick, Perdue, General Motors, IBM, Northrop Grumman, and Verizon.
Split into simpler sentences: Large employers in Maryland include Black & Decker, Legg Mason, Lockheed Martin, Marriott International, McCormick, and Perdue. Other companies with a significant presence include General Motors, IBM, Northrop Grumman, and Verizon.