U.S. railroad operator CSX Corp said on Tuesday Chairman and Chief Executive Michael Ward would retire, effective May 31, after being in the role for more than 14 years.

The company has been a target of activist investor Mantle Ridge LP, which is backing railroad veteran Hunter Harrison to become CSX's chief executive.

Harrison is the ex-CEO of Canadian Pacific Railway Ltd and a turnaround expert highly respected across the industry.

Mantle Ridge has said it owns about 4.9 per cent of CSX's stock.

Last week, CSX said Harrison's proposed pay package was estimated to be $300 million and said Mantle Ridge was seeking substantial representation on the company's board.

CSX said on Tuesday President Clarence Gooden would also retire from the company, effective May 31.

Fredrik Eliasson, currently serving as chief sales and marketing officer, has been named as president, effective Feb. 15.

Eliasson will replace Gooden, who will assume the role of vice chairman until his retirement,CSX said.

CSX said the appointment of Eliasson as president was not intended to pre-empt or otherwise affect any discussions the company may continue to have with Harrison and Mantle Ridge.