I liked The Big Short a lot, but Flash Boys was so bad that I found myself wondering how trustworthy The Big Short was.<p>You can see part of what&#x27;s problematic about the latter book just from this Guardian summary of it. The summary would have us believe that HFT is a trick employed by giant Wall Street banks to screw over smaller players. But Katsuyama, the protagonist of Lewis&#x27; book, was a big-bank trader, paid exorbitant amounts of money to tax large block orders by pension and hedge funds, and outraged by his inability to compete with algorithms that were bidding that tax down.<p>I&#x27;m uncomfortable calling any giant financial firm &quot;trustworthy&quot;, but if you were going to pick one firm that has come close to earning that label, it&#x27;s Vanguard. Vanguard&#x27;s chief investment officer has repeatedly and unequivocally stated that HFT firms have lowered Vanguard&#x27;s costs and improve outcomes for its investors.<p>Here&#x27;s Matt Levine writing entertainingly about how the &quot;Flash Boys&quot; in Lewis&#x27; book ought to have been, based on his previous books, the protagonists, and Katsuyama the villain:<p><a href="http:&#x2F;&#x2F;www.bloombergview.com&#x2F;articles&#x2F;2014-03-31&#x2F;michael-lewis-doesn-t-like-high-frequency-traders" rel="nofollow">http:&#x2F;&#x2F;www.bloombergview.com&#x2F;articles&#x2F;2014-03-31&#x2F;michael-lew...</a>