Isle of Man-based IFA Edgewater Associates (EWA) has bought its rival Knox Financial Services in a £1.7m deal.
The Manx Financial-owned firm will initially take over 4,000 clients and six members of staff, followed by the remaining 150 clients three months down the line.
In total, the business generates an annual renewal income of about £0.4m.
Both acquisitions have already received regulatory approval.
Knox's and EWA's IFA retail businesses have been in direct competition with with each other and have similar client profiles. The client books will be consolidated under EWA's ownership following the transaction.
The deal will increase EWA's combined assets under the management by about £90m to £0.3bn, while the total number of clients post acquisition will be in excess of 11,000, representing 13% of the island's population.
The operating profit of the enlarged EWA business is expected to increase by more than £0.4m, the firm said.
The payments for both transactions will be funded by Manx and will be paid in stages with £0.9m payable at completion, followed by a further £0.2m at the nine-month milestone and a final payment on the first anniversary of each acquisition.
Manx Financial CEO Denham Eke said: "These acquisitions are a very positive development for both Edgewater Associates and Manx Financial Group. We look forward to welcoming our new clients and providing financial advice with a more active and responsive service in wealth management, retirement planning, protection, loan broking and general insurance.
"Our investment in systems means that we will be able to operate the businesses at a reduced cost, both to the benefit of clients and our profitability alike. I anticipate that this will be the first of a number of market consolidations and hope to be able to report further acquisitions in due course."
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