Hargreaves Lansdown increased its assets under administration by £2.2bn in the three months to September, bringing the total to £28.5bn.
In its interim management statement today, Ian Gorham, chief executive, said the results were "encouraging" as the first quarter of the financial year was traditionally quiet.
He said a key driver in the growth of assets had been the stock market, which had risen higher over the quarter.
Revenue was £68.7m, up 20 per cent on the same period in 2011 while the number of active Vantage clients rose by 7,000 to 432,000.

Corporate Vantage scheme members, Hargreaves Lansdown's workplace investment initiative, doubled over the quarter to 9,400. This was due to the addition of 13 new schemes to the initiative.
Net new business inflow of assets was £0.55bn although this was 19 per cent down on the same period last year when it reported £0.68bn. Mr Gorham said this was "pleasing given the trading environment."
On the RDR, the firm has finished modelling its pricing structure and expects to inform clients of the new structure at a later date.
Looking ahead to the second quarter, the firm said it was encouraged to see investors seeking information and becoming clients, helped by the firm's new Sipp loyalty bonus and new share and fund launches. It would also be launching an iPad app to accompany its iPhone and Android apps which have been downloaded 65,500 times.