The debate over high frequency trading (HFT) and whether it will lead to a real life Terminator scenario with computers taking over the world, heated up again with the Knight Capital Group glitch. However, the doomsday scenario seems less likely as details of the Knight case have come out that show it had more to do with a lack of pretty ordinary due diligence than computers run amok.
What failed Knight was a faulty algorithm and poor testing. And, more generally, perhaps the need to be precise in slicing out a tiny edge in the market and then leveraging it up in order to make that tiny edge profitable. Despite all the warnings regarding HFT that involve spooky computer programs, what these traders do is not very different from what the old floor traders have always done. Attempt to find an edge and exploit it. There is this mass of order flow out there from people who are using the market to hedge risk and speculate on the long-term performance of the underlying instruments. Short-term traders have always been content to provide liquidity by constantly making a market and finding small edges. The faster they were, the better access to information and order flow they had, the more successful they could be.
The problem with HFT is that so many people are doing it. It is similar to certain arbitrage trades that exploit small inefficiencies in the market. As more people discover an edge they compete over the same inefficiency until it goes away. But if more volume in the market is coming from folks trying to exploit an inefficiency than the more classical hedgers and speculators, you have a problem.
The question with HFT is if it is a problem that needs to be dealt with through regulation or if it can moderate itself. Are they distorting the market to the detriment of real price discovery or are they simply over extending a slight edge and will go the way of other unsustainable strategies?
In the old floor trading days there were traders who would come in with huge size on the bid or offer. Some suspected these large players where trying to scare the market. They would come in with 1, 2 even 3,000 contracts on the bid or offer. This at times had the effect of scaring folks already on that bid or offer to simply give up the edge. There are those that speculated that was the intention and if they were say 110-18 bid for 2,000 bond contracts, they were secretly offering 200 at 19. This would happen often enough in the 30-year bond pit that some of the big boy locals like Tom Baldwin or Charlie DiFrancesca would occasionally try and keep these folks honest.