The board's June meeting was held in the run-up to publication of the regulator's asset management market study. The report backed the disclosure of an "all-in" fund fee, in line with Mifid II requirements, that would include an estimate of transaction charges.
But the minutes of the board meeting saw respondents suggest that fund houses might downplay these costs in an attempt to make their products look cheaper than rival offerings.
"It was suggested that there needed to be some protection against systematic underestimation of transaction costs which could give firms a competitive advantage," said the board minutes.
"It was felt that this was a supervision task and that monitoring patterns of underestimation would expose such practices."
The FCA's asset management market study did not provide immediate details of how the regulator plans to ensure firms explain their charges to investors.
"We are testing ways to improve the effectiveness of forthcoming disclosure and will consult on any proposals later in the year," the watchdog said in the report.
