Ngai Tahu Holdings Corporation chief operating officer Andrew Harrison has announced his departure after six years with the South Island tribe.
It comes just weeks after Te Runanga o Ngai Tahu sacked Wally Stone as chair of the business.
Interim chair Linda Constable says as far as she is aware the events are not linked.
She says the performance of the group under Mr Harrison's leadership had been outstanding, and included a strategy of partnering for growth with organisations including Christchurch City Council and Talley's Group.
Ms Constable says after Mr Stone's departure and the leaking of an internal runanga report describing the behaviour of Holdings Corporation executives as inadequate, the board issued a statement expressing confidence in Mr Harrison.
However she says the controversy will have had an impact on Mr Harrison as no-one likes to be at the centre of media speculation.
Ngai Tahu Holdings Corporation is now searching for someone with the skills to run a $600 million business.