Assuming that extreme HFT and massive amounts of cancelled orders are BAD (there are people who argue that market liquidity etc. outweighs the drawbacks of short-term focus and billions spent on making algoritms ever faster and moving datacenters ever closer to markets. Let&#x27;s assume they are wrong).<p>How does one change the rules to promote longer term investment and promote quality in trading algos over speed? How do we putting data centers where it&#x27;s cost effective rather than across the street from the market?<p>Adding a <i>random</i> delay to orders which will execute it some time in the next few <i>minutes</i> is one alternative.<p>Having a mandated minimum transaction fee&#x2F;tax is another. What if it&#x27;s 1% (and a nonzero amount for cancelled orders)?<p>Changing the tax structure so that profits from instruments held for less than say a few hours or days are taxed at nearly 100% and then slopes down to a much lower floor for longer term investments (months or years).<p>Obviously any measure has to have wide international support, no market wants to scare the money across the border.