Fund managers also employ dealers who very much do not buy stock one batch an hour so as to allow HFTs to profit from them. They have a fiduciary duty to their

Fund managers also employ dealers who very much do not buy stock one batch an hour so as to allow HFTs to profit from them. They have a fiduciary duty to their clients to aim for best execution, so if they were being disadvantaged they would be crying out to regulators - who like to look after pension funds. The head of Vanguard is on the record saying that his firm benefits from HFTs actions on the market. Narrower margins are a good thing.