Marsh & McLennan Companies, Inc., doing business as Marsh McLennan, is a global professional services firm, headquartered in New York City with businesses in insurance brokerage, risk management, reinsurance services, talent management, investment advisory, and management consulting. Its four main operating companies are Marsh, Guy Carpenter, Mercer, and Oliver Wyman. Marsh McLennan ranked No. 212 on the 2018 Fortune 500 ranking, the company's 24th year on the annual Fortune list, and No. 458 on the 2017 Forbes Global 2000 List. In 2017, Business Insurance ranked Marsh McLennan No. 1 of the world's largest insurance brokers. Wikipedia