Marsh & McLennan Cos. /zigman2/quotes/208419097/composite MMC -0.41% on Monday said John Q. Doyle, 58, will become chief executive officer of the risk advisory and insurance giant on Jan. 1. Doyle has been group president and chief operating officer of Marsh & McLennan since January. From 2017 to 2021, he worked as president and CEO of the company's Marsh unit. CEO Daniel S. Glaser, 62, will retire, "following a decade leading the company through a period of extraordinary growth and change," Marsh & McLennan said. Shares of Marsh & McLennan are down 12.9% in 2022, compared to a 22.5% loss by the S&P 500 /zigman2/quotes/210599714/realtime SPX -0.19% .