Active fund managers have been in retreat in recent decades, assailed by the advancing forces of cheap, benchmark-tracking passive funds, except for one corner where they are gaining market share: the once passive stronghold of exchange traded funds.

ETFs have been on a tear of late, with global assets tripling since the end of 2018 to $14.4tn, according to consultancy ETFGI, as opinions grow that they are simply better than more traditional mutual funds.

Actively managed ETFs have outshone this rate, albeit from a low base, particularly in the US where they have risen 700 per cent since 2019 to $806bn at the end of October, data from Morningstar shows. They now account for 8.1 per cent of money held in US ETFs, while their share of inflows hit a record 27.9 per cent in the first 10 months of this year.