Book excerpt: The debate about high frequency trading (HFT) has been raging since around the beginning of 2010, after a couple of years of record profits in 2008 and 2009 were reported upon by the press with a generally negative tone. But, it was manageable. Regulators were making careful, but mostly correct moves to fix what needed fixing. Until it all came crashing down. With the release of Michael Lewis's latest best-seller, Flash Boys, potential progress was dramatically and possibly irrevocably set back. This e-only book will provide a close look at the topic of high frequency trading in its various aspects: what it is, how it's done, why it matters, and whether we should have concerns.