HFT traders are essentially just market makers The systems you worked on may have fitted into both groups, but your grouping isn't quite right. High frequency

HFT traders are essentially just market makers The systems you worked on may have fitted into both groups, but your grouping isn't quite right. High frequency trading is a broad term that encompasses anything that involves computerised algorithms interacting with a market, and with short position holding periods. MM is a set of strategies which generally requires HFT if you're to be competitive with it on electronic markets.