Aetna Inc. is preparing for a change at the top.

Dr. John Rowe, the chairman and chief executive officer of Aetna, Hartford, is planning to give up the CEO position Feb. 14 and to give up the chairman title at the end of 2006.

Ronald Williams, the president of Aetna, will take over as CEO when Rowe gives up that title, Aetna says.

Rowe will serve as Aetna’s executive chairman from Feb. 14 until he retires, Aetna says.

Rowe, who has been chief executive of Aetna since December 2000 and chairman since April 2001, notes in a statement about his retirement plans that the company’s market value has increased by more than $23 billion, to $27 billion, since its low point in 2001.

Williams, Rowe’s successor, was president of Blue Cross of California, a unit of what is now WellPoint Inc., Indianapolis, when he went to work for Aetna as chief of health operations in March 2001.

Williams became president of Aetna in May 2002, and he joined the Aetna board in September 2002.