Investment consultants are not telling pension funds enough about their fees and performance, according to an initial report from the UK's competition watchdog into the £1.6tn market.

The Competition and Markets Authority began investigating consultants in September, after a referral from the Financial Conduct Authority.  Consultants play a key role in directing how the UK's retirement savings are invested, but the market is dominated by three big players, Aon Hewitt, Mercer and Willis Towers Watson.