Well, keep in mind that this is just an intermediary before the trades hit the rest of the market. If the HFT had not been allowed the advanced access, then th

Well, keep in mind that this is just an intermediary before the trades hit the rest of the market. If the HFT had not been allowed the advanced access, then the transaction would not have been filled in the local exchange and would (or would not) have been filled by the larger market. If another participant besides the HFT algo on the local exchange had been willing to take the other side of the initial price offered, then the HFT firm would not benefit from "probing" for the price. And, what's to stop the entity buying a large quantity of shares from strategizing to account for HFT strategies? The core reason that exchanges offer an advanced look at trades is to try to pull liquidity out of parties that create no transaction fee overhead before passing it to the rest of the market. The price will never be worse than what would have occurred if the trade had been allowed to go out to the rest of the market. The author of the article is essentially just complaining that his own crude algorithm has been outsmarted.