Hedge fund manager Man Group's $1.6bn purchase of GLG Partners last year helped assets under management grow more than expected in its third quarter.Assets under management were $68.6bn at the end of December, including a $25.4bn contribution from GLG, up from $40.5bn in September and slightly more than expected.Man's flagship fund, AHL Diversified, grew AUM to $23.6bn from $22.5bn at the end of September and delivered a total return for the period of 5.3%, taking the calendar year increase to 14.8%.But there were net client outflows for the eighth consecutive quarter, this time $1bn following a single large redemption of over $1bn as an investor switched out of European equities."Investment performance has been the principal driver of asset growth in the final quarter of the calendar year, delivering impressive returns for 2010 as a whole and a solid backdrop for 2011," chief executive Peter Clarke said Thursday.