Rplan has written to its retail customers to tell them it has pulled the plug on its direct-to-consumer investment platform.
From 20 April 2018, the retail platform - which offered investors more than 2,000 funds and a range of risk-based portfolios - will no longer exist.
Customers will have to move their funds or be defaulted to Cofunds' Investor Direct service.
According to Andy Creak, director at Rplan, the decision to close the retail investment platform was difficult because although the platform had good functionality and charging structures, it could not achieve the scale necessary to continue.
In a statement, the company said for retail investment platform to really achieve scale, it would have needed "huge marketing budgets and programmes.
However, bosses decided this sort of capital expenditure would deliver better returns for the company if Rplan focused entirely on its business-to-business proposition.
Mr Creak said: "We are enjoying rapid growth but the best opportunities for us lie in the business-to-business market and not in the direct to consumer one.
"Even though independent research in 2015 revealed we had one of the best investment platforms in the marketplace in terms of charges and functionality, our energy and focus is better suited to promoting and developing our fast-growing business-to-business (B2B) proposition."
As a result, Mr Creak said the company is focusing its attention on the wealth management space.
Mr Creak said the company was piloting a new proposition to help wealth managers with their digital strategies and platforms, which is expected to launch in the first half of 2018.
It has already signed its first client in this sector.
In the past two years, Rplan has seen its revenue increase by 44 per cent, and its workforce more than double to 29.
Also according to Rplan, its investor engagement platform now works with fund managers who together have assets under management of about £22bn - an increase of 53 per cent on three years ago.
Mike Barrett, consulting director at platform consultancy the Lang Cat, said: "The direct investing market is very competitive, and has had a number of new entrants over recent years.
"However, the market remains dominated by Hargreaves Lansdown, which continues to acquire new customers at levels other firms can only dream of.
"With most of the high street banks starting to offer investment services to their customers, it i going to become even harder for smaller start up firms to compete."
Back in 2016, FTAdviser reported on research commissioned by Rplan and carried out by Andrew Hagger of MoneyComms.
This revealed high discrepancies between 21 retail investor platforms in terms of charges, and found that Isa holders with £30,000 invested through a platform could save up to £230.25 a year by switching to a cheaper provider.