Gartmore saw £7.2bn of net new business outflows last year as star managers left and the company started takeover talks with Henderson.
Gartmore, which is set to be acquired by Henderson in April, also revealed a £2.1m interim FSCS interim levy bill in its 2010 results.
Assets under management fell from £22.2bn to £17.2bn while net revenue fell from £223.7m to £208.7m.
The £7.2bn of outflows compare with £300m of net inflows in 2009.
A tough 2010 saw flagship European manager Roger Guy, co-manager Guillaume Rambourg and chief investment officer Dominic Rossi all leave the firm.
At December 31, 2010, Gartmore’s assets under management were £16.5bn, taking into account notifications of redemptions of £0.7bn.
Chief executive Jeff Meyer says: “We were pleased with our progress through the end of the first quarter of 2010 but events after this caused us to consider other strategic opportunities in order to preserve value for shareholders and maintain client support. In view of this, the proposed transaction with Henderson Group represents a good outcome for shareholders while ensuring continuity for clients.”
Henderson says portfolio managers, who run 84 per cent of Gartmore’s assets, have agreed to remain with the combined group after acquisition. The managers include John Bennett, Chris Palmer, Chris Burvill, Ben Wallace, Charles Awdry, Adam McConkey, Tony Lanning and Luke Newman.
Chelsea Financial Services managing director Darius McDermott says: “We have no problem investing in any of the Gartmore funds which have been run by managers that are moving across to Henderson but you do expect these outflows when there is an acquisition as people are weary of future changes on the horizon.”