The deal was first announced in February.

Third Financial is a provider of white label investment platforms and software.

Nucleus said the acquisition expands its capability in the ‘adviser-as-a-platform’ space. 

Richard Rowney, chief executive of Nucleus, said: “By combining the businesses we can now develop bespoke platform solutions for any client. We look forward to the next chapter in our growth journey with the integration of Third, and to developing the opportunities opening up to us to serve the wider wealth sector.”

Ian Partington, chief executive of Third Financial, will continue to lead the business reporting to Mike Regan, chief commercial officer of Nucleus.

Mr Partington said: “We look forward to the opportunities ahead as part of a larger group.”

Nucleus Financial Platforms currently has more than £80bn of assets under administration for 250,000 customers and owns a number of subsidiaries including James Hay, Nucleus and SIPP provider Curtis Banks, a recent acquisition.

Third Financial provides an investment platform and wealth management software. It serves discretionary wealth managers, multi-family offices and adviser consolidators.

Third Financial has seen growth in recent years with revenue increasing by more than 30% in 2023, it said. It has more than 50 clients in the UK and a total of £6bn in assets under administration on its platform and a further £40bn of assets administered via its software system Tercero.