(Reuters) - Lockheed Martin Corp
Hewson, who ranked No.4 in Fortune magazine's list of the most powerful women in U.S. business for 2013, will become the chairman on January 1, a year after she was appointed chief executive.
Stevens will retire from Lockheed in early 2014, the company said.
Hewson took the top job at Lockheed after Christopher Kubasik was fired when he admitted to an improper relationship with a subordinate.
(Reporting by Sagarika Jaisinghani in Bangalore; Editing by Kirti Pandey)