Dimitris Papoulis, Pioneer Marine's chief operating officer, has assumed the position of chief executive, replacing Torben Janholt.
Janholt, who has led Pioneer since inception as a board member, "has decided to end his journey and pursue his personal objectives", the company said.
He will also step down from the board of directors, effective tomorrow. Chief financial officer Korinna Tapaktsoglou will take his seat on the board.
