Insurance giant

Aetna

(AET)

said William Donaldson will step down as chairman, but will remain a member of the board of directors.

John Rowe, the company's president and chief executive, will assume the role of chairman when Donaldson steps down on April 1.

Donaldson, a co-founder of investment bank

Donaldson Lufkin & Jenrette

, joined Aetna as president, chairman and CEO in February 2000. He stepped down as president and chief executive last September.

The company, which is based in Hartford, Conn., also named Ronald Williams as executive vice president and chief of health operations. Aetna named William Popik chief medical officer on March 5.

In recent trading on the

New York Stock Exchange

, Aetna was down 66 cents, or 1.8%, to $36.92.