HFT firms will try to detect when equities traders are doing this. e.g. If they see a pattern indicating that chunks of shares are being bought, they will try t

HFT firms will try to detect when equities traders are doing this. e.g. If they see a pattern indicating that chunks of shares are being bought, they will try to buy, too. Price discrimination against large traders - grandma gets a better price than Bill Ackman - is a valid and real HFT strategy. They do it in the manner you describe. But it's not front running. It's only front running when your agent (usually your broker) does it based on private information. Front running is just a term Michael Lewis misused in his misleading advertisement for IEX.