Marsh & McLennan Companies (MMC) is a heavyweight insurance middleman. The company is one of the world's largest insurance brokers. Through core subsidiary Marsh, the company provides a broad array of insurance-related brokerage, consulting, and risk management services to clients in more than 130 countries including large and small companies, government entities, and not-for-profit organizations. Its global reinsurance brokerage business is handled by subsidiary Guy Carpenter. MMC also owns Mercer, which provides human resources and financial consulting services to customers in 40 nations worldwide; and Oliver Wyman, which provides management consulting services.