Ahem, buried in the middle of the article (I wonder why)  &quot;Navinder Sarao is accused of spoofing in the S&amp;P 500 futures market, entering and cancelling lots of orders to create an illusion of demand, in suspicious proximity to the flash crash of 2010.&quot;<p>This happens a lot more than you might think.  There is always a temptation to stuff the order book to keep it going in a direction profitable for you (ie, fake volatility).<p>This is the #1 reason why canceled ordered from HFT are suspect.   It&#x27;s too easy to stuff the order book and cheat a little.   You really need highly credible market makers who have proven not to do this sort of thing.   Even then, such folks are very rare and hard to appreciate.  Your algorithms get so complex and obfuscated it&#x27;s hard to tell what&#x27;s stuffing the order book and what&#x27;s simple market making.<p>The fact is, everyone is stuffing the order book.   Sarao is more a patsy than anything else.  His biggest crime wasn&#x27;t belonging to a Goldman Sachs paying bribes to political entities.