There is debate as to how beneficial a bought share can be to a company who has it sold back within a second. The question has to be asked not from the simulation of one investor, but of a whole system of investors behaving as such. HFT companies tend to be very in-house about their money. (Jane Street accepts investment only through employees.) If HFT is giving a net profit, it might not be giving a net profit in a fair and uniform manner. It may be concentrating capital towards only those who can get a supercomputer connected to the stock market with fiber optic cable. Regulation requires micromanagement of laws to react whenever a loophole is found, as profits begin to show up immediately (Allows for more experiments, thus causing a more volatile/innovative field.) While high frequency