High Frequency Trading: All You Need To Know

"So the bottom line: HFT is legal frontrunning... but also so much more.  In fact, like the TBTF banks, HFT itself has become so embedded in the topological fabric of modern market structure, that any practical suggestions to eradicate HFT at this point are laughable simply because extricating HFT from a market - which indeed is rigged but not only by HFTs at the micro level, but more importantly by the Federal Reserve and global central banks at the macro - is virtually impossible without a grand systemic reset first. Which is why regulators, legislators and enforcers will huff and puff, and...  end up doing nothing. Because if there is one thing the TBTF systemic participants have, is unlimited leverage to collect as much capital due to being in a position of systematic importance in a market, rigged or otherwise.
Finally, if push comes to shove, and the fate of HFT is threatened, watch out below, because if HFT's presence, glitchy as it may have been, led to the May 2010 flash crash and the subsequently unstable market which has exhibited at least one memorable crash every single month, then the threat of pulling the marginal trader which now accounts for 70% of all stock churn and volume (if certainly not liquidity) would have consequences comparable to the Lehman collapse."