NBR Rich Lister Colin Armer has resigned from Fonterra's board, effective immediately, days after being overlooked for the top job.
Mr Armer, a director since 2006, did not state his reasons and a statement from PR company Senescall Akers says the Dairy Holdings director will not be available for comment.
His resignation comes just days after John Wilson was named as the dairy giant's new chairman, replacing Sir Henry van der Heyden.
A well-placed Fonterra source says: "Obviously he doesn't feel he can support the chair."
Online trading site iPredict started a poll in April, on "Colin Armer to be next chairman of Fonterra". The last trade was made on Monday morning.
Last month, Mr Armer's company, Armer Farms (NI), was fined $72,000 in the Tauranga District Court for fouling a Bay of Plenty stream.
In the Senescall Akers statement, Mr Armer says: “For many years I have been, and continue to be, a strong supporter of the New Zealand dairy industry and an advocate for Fonterra’s important work. I will continue to be."
Mr Armer is locked in a High Court battle with Dairy Holdings founder Alan Pye, who is challenging Mr Armer's attempted seizure of control of Dairy Holdings.
Multimillionaire Mr Pye claims Mr Armer broke pre-emptive share rights and took out loans against Dairy Holdings shares he holds in trust on behalf of other parties.
Dairy Holdings owns about 58 farms and has estimated assets of around $600 million.
If you have more information on Colin Armer's resignation, email David Williams.