I have no idea what the mechanism is, but there&#x27;s definitely something extremely fishy when you don&#x27;t see the NBBO move <i>at all</i> for an hour and it magically moves the moment you place an order. I wouldn&#x27;t even know who is to blame: Interactive Brokers? Other HFT players? My incredibly consistent bad luck at placing an order <i>at the exact same moment</i> the price goes up, even after observing the price being stable for an hour (again, at a very low volume time of day, like 3pm PST)?<p>I clearly don&#x27;t understand what&#x27;s going on under the table as well as you would, and because the strategy I was toying around with at the time was basically big volume on small spreads (&quot;big&quot; for a retail guy, obviously, I don&#x27;t have millions at my disposal) it was shot to crap by these magic changes.<p>So I did the sensible thing and closed my account. Off to invest in less volatile assets, if I can find any, heh.