Assets managed by private client stockbroker and fund manager Hargreaves Lansdown jumped by more than 20% in the past three months as rising stock markets 'galvanized investors into action'.Total assets under management jumped by 22% to £14.5bn at end September, compared to £11.9bn at end June and £10.3bn a year ago.Vantage, Hargreaves's private investor platform, boosted its managed assets from £10.7bn to £13.1bn, split £0.56bn of net new business inflows and £1.9bn of market gains. Its own range of multi-manager funds and Portfolio Management Service increased assets by 21% to £1.7bn.Operating revenue for the first quarter was up 13% to £36.1m. Vantage division revenue increased by 21%. Higher average asset values compensated for the reduced revenue margins achieved compared to the same period in the previous financial year. 'The rise in stock markets throughout the world has made a huge impact on the value of assets under our administration. This, together with unusually high inflows during the summer months, has produced a gratifying boost to group income,' chief executive Peter Hargreaves said.'Although we are impacted by the decline in the margin we make on cash deposits, our primary business of gathering assets together with the rise in stock markets has more than compensated for this loss of income,' he added.