Fonterra chairman Sir Henry van der Heyden, who was due to stand down at the end of this year, has agreed to stay on as a board member until the co-operative's Trading Among Farmers scheme gets off the ground.
The share trading plan is set to be launched in November, depending on market conditions, and Sir Henry will stay on in his farmer-elected term which runs until the end of 2013.
Due to other commitments however, he is expected to leave part way through next year.
Non-farmer director Ralph Waters, who was due to step down in December, will stay on for up to six months longer.
Fonterra Shareholders' Council chair Ian Brown says the decision to retain the services of Sir Henry and Mr Waters into 2013 would provide stability for the introduction of Trading Among Farmers.