According to the efficient market hypothesis, information can only be valuable until there has been time for information to circulate through the market, and th

According to the efficient market hypothesis, information can only be valuable until there has been time for information to circulate through the market, and the market price to reflect that information. This seems to happen in under 15 minutes. That's why 20 minute delayed ticker prices are generally available for free. HFT lives on happening so fast that the market price has not had time to catch up to the information that a trade is available. But it is a race against others in the same market. And an incredible amount of effort has gone into winning that race and making profits off of the increasingly narrow slice of time that markets are profitably inefficient for.