HFT firms aren't trying to predict "the market" as a whole - just small eddies of it. A typical example of this is arbing names at the bottom of index fund reba

HFT firms aren't trying to predict "the market" as a whole - just small eddies of it. A typical example of this is arbing names at the bottom of index fund rebalances. Speed is important mostly to make sure someone else doesn't hit the arb first.