John Dyer, chief operating officer of Atlanta-based Cox Enterprises, will assume the role of president and chief executive officer on Jan. 1, the company announced Thursday.

Dyer will be responsible for the company’s four main subsidiaries: Cox Communications, a cable TV provider; Manheim, a wholesale vehicle marketplace; AutoTrader Group, an online auto classified marketplace; and Cox Media Group, a broadcasting, publishing and digital media company. Cox’s holdings include The Atlanta Journal-Constitution.

Dyer, a 36-year company veteran, will replace retiring CEO Jimmy Hayes, who has been with the company for 33 years and has served as president and CEO since 2008.