Hargreaves Lansdown increased its profits before tax by 12 per cent to £146.9m during the six months until the end of December 2017.
During that period the company saw net new business of £3.34bn and increased its client bank by 61,000.
The FTSE 100 company saw its net revenues increase to £216m, thought its costs also increased to £71m.
Hargreaves Lansdown ended the six-month period with assets under administration up by 9 per cent to £86.1bn.
Chris Hill, the chief executive of Hargreaves Lansdown, said: "Our leading reputation for client service and the breadth of our offering appeal to new clients who, in common with our existing clients, transfer and consolidate their investments onto a single platform and then regularly contribute and take advantage of their annual allowances as they build their own and their family's wealth.
"Our proposition and scale also enables us to help fund managers in transferring direct back books and we were pleased to welcome clients arriving from BlackRock in the period and Old Mutual due later this year.
"We should also recognise that operational issues on a competitor platform resulted in significant levels of transfer activity across the period."
Mr Hill added that the company faced a "significant" market growth opportunity because of the long-term savings gap and the increasing requirement for individuals to have greater involvement in their savings.
Despite this, Mr Hill reported that the launch of Hargreaves Lansdown's cash management service had been delayed.
The service, called Active Savings, was launched in December but Mr Hill said it would grow through the first half of 2018 with a "measured rollout" which began with 1,000 clients.
He said: "Although it has taken longer to launch than originally planned, we believe it will make the management of cash savings simpler and easier than ever before, all at the same levels of client service as the rest of our offering.
"Further developments are planned through 2018 and beyond, including the addition of further banks, easy access accounts and the Isa and Sipp cash capabilities into the service."
Revenues at Hargreaves Lansdown increased by 17 per cent, with the company's higher average assets under administration and increased client share dealing activity pushing this up.
Of the company's revenues, £97.8m came from platform fees and renewal commission while £42.9m came from stockbroking commission and equity holding charges and £33.3m came from the annual management charge on the multi-manager HL Funds.
Hargreaves Lansdown increased its staff costs by 31 per cent to £41.8m as the number of staff increased from 970 to 1,310.
In its results, the company said: "We consciously and significantly increased our investment in people, digital marketing and technology during the 2017 financial year as we believe the group's focus on client service is core to our success as a business and necessary to position us to capture the structural growth opportunity in the UK savings and investments market.
"This has been validated by the strong net new business levels we have seen across the past 12 months, high client retention rates and continued development of our product set and growth capabilities during the period."
Hargreaves Lansdown said it would be launching a new visual identity next week to help drive its profile following an investment in marketing and distribution of £6.9m.
damian.fantato@ft.com
