HFT provides liquidity . . . I always see this argument. Market makers provide liquidity, and yes, HFT often act as market makers. However, I am not at all co

HFT provides liquidity . . . I always see this argument. Market makers provide liquidity, and yes, HFT often act as market makers. However, I am not at all convinced that the high frequency element adds anything useful to the equation. I don't care whether my trade executes in a microsecond or a second. In fact, I often leave limit orders open for DAYS in order to get the price I want. I am also not convinced that most HFT are truly acting as market makers. I think the most charitable thing that can be said about HFT is that it narrows the spread. In order to make it worth their while, the HF traders then have to make a lot more trades. Whether this is adding any real value to the system is harder to say because while the spreads are smaller, the volatility is higher.