Because barriers to trade have worked so great in the past...<p>This is just another fluff piece without too many rational arguments, based on a completely irrational fear of HFT. Arguably, HFT and hedge fund have made the markets much more micro-efficient in the past decades (as wittnessed by the difficulty of finding new arbitrage opportunities); we have to thank the central banks and big institutional investors for macro-inefficiency.<p>&gt; one that applies a tiny tax rate to an array of transactions and is split between buyers and sellers<p>I think the current situation, where exchanges basically &quot;tax&quot; those who take liquidity and reward those who provide it (i.e. the fee of a market order is split between the exchange and the person who entered the limit order) is much better at providing stability to the market.<p>&gt; which generate windfall profits on small and fleeting differences in prices at the expense of ordinary investors and market stability<p>Well, the idea behind is that prices (e.g. same stock on different markets) should converge. If you don&#x27;t want that, by all means, tax the market.<p>&gt; The burden of this tax would be concentrated at the top, because that’s where the ownership of financial assets is concentrated<p>Nope, it doesn&#x27;t matter where <i>ownership</i> is concentrated. What matters is where <i>trading</i> is concentrated. E.g. HFT or every time you get paid and invest a portion in your income in a stock index-backed pension scheme.