HFT doesn't move markets; it simply takes advantage of the lag between information becoming available and the market's response. By doing this, HFT makes the ma

HFT doesn't move markets; it simply takes advantage of the lag between information becoming available and the market's response. By doing this, HFT makes the market respond to information faster. This is how arbitrage works. If there is an inefficiency in the market (e.g. the speed with which the market reacts to information), someone can take advantage of it. By taking advantage of it, the inefficiency disappears. Eventually, the arbitrage becomes commoditized and the "value" of the arbitrage situation is a few points above the cost of the solution. You can't apply morality to financial markets. All investments carry risk, and its up to each individual investor to choose securities in line with their personal risk tolerance. If the investor doesn't understand the risks involved in a security, they shouldn't be making investment decisions, full stop. If you're like the majority of US retail investors, you're buying a stock and holding it for a long time. HFT doesn't really affect you in that case, because they play both short and long positions alternated many times throughout the day, yet averaged over a period of time it's a zero sum game. A good analogy to think of are Riemann sums vs. integrals in calculus. The actual movement of the market is the curve, but you don't know the formula of the curve and you need to measure the area under it. So you approximate the curve by sampling a number of points (the current price of the stock at any given moment) and calculating the distance from the axis. HFT effectively allows you to sample more points, getting a more accurate result by removing "arbitrage" (or space between the sampled points and the actual curve).