Funds under management at St James's Place climbed £2.4bn to £24.8bn in the three months ending 30 September, and have now doubled over the last five years.
The company says a "welcome" recovery in global stock markets helped it achieve a net inflow of FUM of £700m in the period, up £100m on last year.
It said it continues to retain 95% of existing clients' funds.
Elsewhere, total new business on an APE basis jumped 30% to £136.5m, again compared with 2009.
Total single investment advanced 32% from £0.8bn last year to £1.1bn in Q3.
Regular premium business increased 23% to £26m, thanks largely to a 31% jump in pensions business regular premiums.
"We are delighted with the continued momentum in new business and investment inflows during the quarter, which is attributable to the increasing breadth of our investment offering and the strength of our distribution," CEO David Bellamy says.
"This performance, together with the recovery in world stock markets, has given rise to strong growth in funds under management to £24.8bn.
"Although the outlook was uncertain earlier in the year, 2010 is proving to be a very successful year for St. James's Place.
"While we are up against tougher comparatives in the short term we remain confident in our ability to deliver average new business growth within our 15-20% per annum range over the medium term."
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