Mifid rules drive growth of passive investments

But Paul Boughton, founder of MosaicNED, a company that provides training for directors, said the requirement under the Asset Management Market Study rules for independent directors to be appointed to funds was likely to drive fees lower.

Under the rules, open-ended funds must appoint directors, with 25 per cent of them being independent and non executive.

Investment trusts are already required to have independent directors. Data from the Association of Investment Companies (AIC) shows that since 2013, 156 investment trusts have cut the management fee.

Mr Boughton, who had previously worked in sales roles at Neptune, Schroders and Mirabaud, said: "As long as the directors chosen are properly independent and diverse, and not just mates of the fund manager, then I think one of the ways they will add value is to question the fees, and we could see something similar happen as has happened in the investment trust world."

The inevitability of fund management fees falling has been acknowledged by some in the industry, with Maarten Slendebroek, former chief executive of Jupiter, stating he expects his firm's profit margin to fall by about a basis point a year on average in the foreseeable future.