Transact's funds under direction (FUD) increased to £31.88bn at the end of June 2018, a rise of 7.2 per cent on the previous quarter.
A market update from Integrafin, Transact's parent company, said this meant funds on the platform were 14 per cent higher than at the start of the company’s financial year.
The increase has been attributed to £959m of net inflows, with the positive performance of stock markets contributing £1.14bn, compared with £194m in the previous quarter.
Ian Taylor, chief executive of Transact said: "We report another solid FUD update. Net inflows for the financial year to date are 18.5 per cent ahead of last year and outflows have decreased as a proportion of opening FUD (4.8 per cent vs 5.4 per cent)."
Mr Taylor had previously told FTAdviser that for every £1 withdrawn from the platform, about £10 was being placed onto it by clients.
Integrafin floated on the London Stock Exchange at the end of February with a value of £649m.
But the company's shares have performed strongly since the business came to market, with its share price rising from £2.58 at the time of the float to £3.85 this morning (24 July).
Integrafin's strong performance on the stock market saw it promoted to the FTSE 250 in May.