Hargreaves Lansdown has increased its assets under administration by £400m since flotation in May.
Assets under administration grew from £10.2bn to £10.6bn between June 30 and September 30, the first quarter of its financial year.
The increase came through its Vantage platform, which saw assets rise from £9.1bn to £9.5bn. A further 5,000 clients signed up to the platform, bringing the total to 223,000.
Net inflows into the Vantage Isa were up by 70 per cent while Sipp sales rose by 50 per cent compared with the same period last year.
Chief executive Peter Hargreaves says the results are particularly encouraging as the FTSE All Share index fell by 2.6 per cent over the quarter.
He says: “It is difficult to draw too many conclusions from the first quarter of trading. However, we are pleased that despite the less favourable market conditions, we have continued to attract new clients into Vantage and existing clients continue to entrust us with more of their wealth.
“We remain confident of our prospects for the remainder of the financial year although the market will have some say in our overall performance.”