President and CEO Henry "Hank" Newell will also step down from the company's board of directors. Wausau Paper says board chairman Thomas Howatt will retire.
Daily Herald Media says Wausau Paper has been under pressure from a New York hedge fund, Starboard Value LP, which has repeatedly sent letters to other shareholders expressing a lack of confident in the company's management.
An interim CEO, Michael Burandt, has been appointed. He has the backing of Starboard and will become chairman of the board.
The once dominate employer in central Wisconsin has shut down its mills in Brokaw and Brainerd, Minn., in recent years and has sold facilities in Rhinelander and Mosinee.