A group of 17 Artemis fund managers and key staff have agreed to a five-year lock-in preventing them from leaving or selling shares in the company before 2015.
The deal forms part of the sale of the boutique to the fund managers and the US Affiliated Management Group (AMG).
AMG, the Boston-based fund management group, and the firm's key staff have taken over the boutique for an undisclosed sum.
The deal ends two years of uncertainty for Artemis. AMG came close to buying Fortis's stake in September 2008, but the deal was held off amid the financial crisis.
In October 2008, Fortis was forced by a change-of-control clause to pay £330m to 14 Artemis fund managers for the third of the business they owned.
When Fortis was broken up last year, Artemis passed to BNP Paribas. Towards the end of 2009, it put Artemis up for sale again.
Mark Tyndall, co-founder and chief executive of Artemis, says it was a relief to end months of uncertainty during which assets under management fell from a peak of £17bn in 2007, to the current £10bn. Assets managed for institutional clients fell from £8bn to £4bn.
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