Marsh & McLennan Companies is a global professional services firm founded in 1871 with over 57,000 employees worldwide. It has four main businesses: Marsh, Guy Carpenter, Mercer, and Oliver Wyman. The company provides risk management, insurance broking, reinsurance services, management consulting, and human resource consulting to clients in over 130 countries. It has a long history of growth through acquisitions and expanding globally to become a leader in its industries.