“Concentration is hard to predict; it’s really hard to guess when it ends. For that reason, one of the best defences against it is to be invested in passive management as well,” he said.

Fisher said the fund was not “becoming enthusiastically active”, but rather was moving to a more neutral position with a 60/40 split in favour of passive investment.

Meanwhile, Rest Super chief investment officer Michael Clancy said the concentration in markets could not be put down wholly to passive investors, and said the onus was on active managers to prove they can “add value [for funds] in a way that justifies the fees paid to them”.

Clancy said that his $100 billion fund was more likely to allocate more cash to strategies that tread the…