Institutional clients withdrew £1bn of assets from the Cofunds platform in the three months to 30 September, while retail advisers appear to be keeping faith with the beleaguered business.
Data from Fundscape, a consultancy firm, showed assets under administration on the platform had fallen £1.07bn in the quarter, which Aegon, Cofunds' parent company, put down to flows from institutional clients.
An Aegon representative said the company had also observed lower trading volumes from retail clients in the period but added this was merely "a secondary factor".
The data showed Cofunds had seen one of the biggest inflows of all platforms in the quarter, having attracted £7.4bn of new sales. But the outflows offset the sales which meant the platform did not appear among the top five platforms in terms of net sales.
It is unclear which clients have withdrawn their funds from Cofunds but institutional clients on adviser platforms generally include discretionary fund managers (DFMs), which use the platform purely for trading purposes. Such companies find it easier and quicker to switch between platforms because they do not have to move multiple client accounts, as the DFM business is 'the client'.
Retail advisers on the other hand have to show how it is in the interest of each and every client they want to switch.
An Aegon representative explained: "The institutional service enables other providers to buy and sell funds on a bulk basis. We manage the trading and settling of funds on their behalf but have no relationship with the end customer and are essentially processing these transactions on behalf of their chosen provider."
Jenny Griffiths, an adviser at CP Griffiths and Co in the West Midlands, has previously told FTAdviser of the lengthy process of time and effort it took for her to transfer her clients off the platform.
Ms Griffiths decided to transfer her own account off the platform as a dry run, when she encountered delays in completing the transfers. She claimed her business was losing about 10 per cent of turnover due to time spent sorting out Aegon related matters.
Ms Griffiths has told FTAdviser she still hasn't been able to transfer all of her clients off the platform and claimed she has "not noticed an improvement in the turnaround time".
But Aegon said all of the transfer requests are currently being processed in the targeted timeframe, which was six working days for initiating a transfer.
The provider had acknowledged at the time that transfers were taking longer than expected, albeit some of the delays had been caused by gaps in adviser submissions, it said.