If it makes you feel any better, I don't work for an HFT firm. Instead, my job involves trading against them. To do that effectively, it's necessary to understand what they're actually doing and how they make their money.
I speak up here because it irritates me to see them maligned by people who know what they're talking about.
I speak up here because it irritates me to see them maligned by people who know what they're talking about.