The largest insurance brokerage firm in the United States and globally, measured by annual revenue, is Marsh McLennan (Marsh & McLennan Companies). Generating over $25 billion in annual revenue, it leads the market in commercial risk management, insurance broking, reinsurance solutions (via Guy Carpenter), and workforce consulting (via Mercer). Other massive domestic peers include Aon, Arthur J. Gallagher, and Willis Towers Watson.