Read this old, unsurprising report in New Scientist. From the article:
Automated trading ...has come to account for more than half of trades in many markets around the globe. ...Because of the finite speed of light, trading speed depends on where you are sitting. ..."The basic insight," says Wissner-Gross, "is that the optimal location lets the trader exploit fluctuations equally on both exchanges." ..."This shows that the technological arms race to extract every penny from high-frequency mechanical arbitrage will soon reach its ultimate limits," says physicist and hedge-fund manager Jean-Philippe Bouchaud
If this is how money and the free markets work now, I'm pretty sure we no longer know what words mean.