Lockheed CEO Marillyn Hewson to step down

Lockheed Martin's Marillyn Hewson is stepping down as CEO. After more than six years in the corner office, she'll remain with the company but move to the executive chairman post in June.

Under her six years at the helm, shares of the Pentagon's largest defense contractor more than tripled. Helping boost the stock: the F-35 fighter jet, which makes up about a quarter of its revenue, as well as military contracts benefiting from increased U.S. defense spending. Lockheed had changed its mandatory retirement age rules in 2018 that allowed her to remain past 2019.

Succeeding Hewson will be Lockheed board member James Taiclet. Currently chair and CEO of telecom infrastructure developer American Tower, he's a veteran of the aerospace industry, having served in senior executive roles at units of Honeywell and United Technologies. He was selected over two internal executives who were seen as prospective successors.

Lockheed Martin shares tumbled after the market opened Monday amid a huge across-the-board sell-off on Wall Street.