Brian Gaynor's Milford Asset Management and businessman Andrew Barnes have bought New Zealand Guardian Trust for $68.5 million.
The business was purchased from Australia-based Perpetual.
At the same time Mr Barnes' Bath Street Capital has completed the $22 million purchase of Perpetual Trust New Zealand, which has no connection with the Australian Perpetual.
Mr Barnes said the two companies would operate under a single board which would oversee their direction and he would be chief executive of both.
He said there were good reasons not to merge the two companies. They were largely complementary, he said. Perpetual no longer has corporate clients while their private clients were split between the North and South Islands.
Mr Gaynor said Milford believed the acquisition would be good for those clients who had invested in their Active Growth Fund and Active Growth Kiwisaver Fund, the vehicles investing in Guardian Trust.
Andrew Barnes said they were looking to bring new products to New Zealand and were not ruling out opening more offices.