An alliance between the commercial arms of Ngai Tahu and Tainui have led to the groups buying the passenger transport company Go Bus for a total of $171 million.
Ngai Tahu Holdings Corporation and Tainui Group Holdings have conditionally purchased it from Australian firm Next Capital.
Go Bus operates urban and charter services as well as running school buses throughout the country.
Tainui Group Holdings chief executive Mike Pohio said it would have a one-third share in the business. Ngai Tahu Holdings Corporation would be the majority investor holding the remaining two-thirds.
Mr Pohio said the iwi partners' mandate was for reinvestment and growth and Go Bus was a well-run business that would allow the tribes to grow and diversify further.
He said there were other factors as well as commercial ones that became influential elements in their decision to buy the company.
Mr Pohio said the business minimised its carbon footprint, about 10 percent of the Go Bus workforce have Tainui affiliations and there were opportunities for employment.
Ngai Tahu Holdings Corporation chief executive Mike Sang said it was exciting for the iwi to make what they saw as a sound investment that added to their investment portfolios.
Mr Sang said investing in public transport was appealing due to its expected growth as the population increased, as well as helping address environmental concerns.
The purchase is due for completion on 30 September.