Besides Devon, ISG runs JMI Wealth, Select Wealth, Clarity Funds and TAHITO.
JMI Wealth will be rebranded to the Shaw and Partners brand.
Shaw and Partners is a subsidiary of Swiss private bank EFG International which specialises in wealth management and investment management.
It has A$35 billion of assets under advice in Australia, while ISG has $7 billion in New Zealand.
“Shaw and Partners offers the intimacy of a boutique investment firm, backed by the resources and scale of a major global financial group in EFG International,” the companies say in a press release.
Across its overall group, EFG International manages about $330 billion of assets and has a market capitalisation of around $7 billion and is regarded as one of the best-capitalised Swiss private banks.
ISG chairman Paul Glass says the group started a strategic review last year.
“At the outset of our process, we indicated our desire to find a long-term partner who could accelerate our growth. At the same time, it was critical to us that we found a partner that would allow us to continue the journey together.
“Shaw and Partners represents a very strong fit for us given these considerations.
"Shaw and Partners has a particular focus on developing long-term relationships with clients that are founded on trust, which we believe is perfectly aligned with our approach to client partnerships. We were also attracted to EFG International’s global expertise in wealth and investment management, strong financial position and its track record of solid growth," Glass says.
"Our current management team and key shareholders have made a long-term commitment to our partnership with Shaw and Partners, which we believe is critical to a successful next chapter for ISG."
Shaw and Partners chief executive Earl Evans says "we believe that great businesses are built on strong relationships—with clients, with communities, and most importantly, with each other. That’s why this partnership is about more than scale or strategy. It’s about shared values. It’s about bringing together two like-minded firms with a focus on doing the right thing by clients and empowering our people to do their best work."
"The ISG team are joining a group that celebrates initiative, backs its people, and believes in the power of collaboration. Together, we have a great opportunity to grow, and to build something even more extraordinary in New Zealand."
Meanwhile, JMI Wealth managing director Andrew Kelleher says the firm will rebrand and look to grow its adviser force.
"We believe there will be compelling reasons to work with Shaw and Partners (NZ). As the New Zealand market continues to evolve and consolidate, it is our sense that more and more advisers will find that partnering with Shaw and Partners (NZ) provides the ideal platform to deliver a superior service to clients."