Investors withdrew a net £110m from five of the largest platforms in September, according to latest data from the Investment Association (IA).
The platforms, Hargreaves Lansdown, Aegon, Old Mutual Wealth, Transact and Fidelity, suffered £569m in outflows from their unwrapped assets in the month.
Meanwhile, personal pensions had net sales of £453m, insurance bonds £6m, and Isas £1m, according to the IA.
The platforms had combined funds under management of £280bn at the end of September 2018, up 11 per cent on the £252bn they held a year earlier.
Net retail sales overall swung into the positive in September, with £642m of inflows from UK authorised and recognised funds, and funds under management totalling £1.3trn.
Gross retail sales for UK fund platforms in the month totalled £8.2bn, representing a market share of 47.2 per cent, up from 43.9 per cent in September last year. This compared with intermediary sales of £4.2bn, and direct sales of £1.5bn.
Jason Hollands, managing director for business development and communications at Tilney noted that investors continued to flee UK equities, with net withdrawals of £309m in September 2018, but said this was better than the average monthly outflow of £406m over the past year.
European equities also saw net outflows in September, with investors withdrawing a net £58m, compared with an average inflow of £100m over the past year.
The best selling sector was the IA Mixed Investment 40-85 per cent shares, which saw inflows of £268m.
Chris Cummings, chief executive of the Investment Association, said: "Uncertainty continues to be a driving factor for investors, with global and mixed asset funds benefiting, as savers look to diversify and manage their risk.
"September saw net retail sales bounce back into positive figures, however UK equities continue to remain firmly out of favour, with European equities experiencing a fifth consecutive month of outflows."
Investor caution in September may have been prescient, as data from Financial Express showed every sector in the IA fund universe posted a negative return in October, with the exception of the IA Index Linked Gilts segment of the market.
Index Linked Gilts, unlike most other bonds, pay an interest rate that floats as interest rates or inflation moves up or down, and so offer protection for investors from higher inflation.
The sector delivered a positive return of 1.22 per cent in October, a period that coincided with a rise in the oil price and a fall in the value of sterling, both events that would be expected to cause UK inflation to rise.
The picture for UK equities was less positive, with a negative return of 8 per cent in October.
Mr Hollands said the negative sentiment was a direct result of worries around Brexit and if there is no hard Brexit the UK market could "rally hard".
Ben Yearsley, investment director at Shore Financial Planning, said the month of October was a "poor month" for all asset classes.