The IAAF chief executive Olivier Gers has quit after just 18 months in the role.
Athletics' governing body has announced his exit after he was appointed in October 2016.
Gers will continue in his role for the next three months but said he was ending his stay because of issues with the commercial framework.
He said: "Whilst I am sorry to be leaving, the pre-existing commercial framework makes it difficult for me to apply my talents and fully leverage the assets of the IAAF in the way I would like.
"Given my stance, I have resigned so the IAAF can pursue a different commercial strategy for the sport.
IAAF president Sebastian Coe added: "I would like to thank Olivier for the work he has done particularly around putting a strong team in place at the IAAF, developing a strategic plan and securing broadcast and digital rights to expand audiences for athletics globally. "