This sounds like liquidity is a bug rather than a feature, because those secondary trades don't send capital to the companies. But that liquidity is part of wh

This sounds like liquidity is a bug rather than a feature, because those secondary trades don't send capital to the companies. But that liquidity is part of why the primary capital went into the company, and that liquidity supports a flock of risk management and information signalling functions. So I'm not sure why the focus on liquidity per se. Given that the rejection of HFT has to be overbroad. If they liquidity they provide is the sort of that supports the functions we like, who cares what their holding periods are? It certainly seems true that Cuban is right about "hacking" the market insofar as yeah, a good deal of HFT sounds like exploitation of rules and procedures to avoid creating the fair market intended. But that means there is "bad" liquidity, which doesn't serve our purposes. Okay, so let's write rules that better serve our purposes for liquidity. (And if we're worried about market distortions from bad trading liquidity, what about the market distortions from Fed provision of currency liquidity? The wash of cash has lifted all asset prices, it's hard to see economic signals when price correlations are moving to one.) Cuban seems to think we can do just that by manipulating investor incentives -- give them tax breaks for holding periods, tax transactions, etc. But all of these just make the market more complex, and increase the differential between investment categories -- all of which creates more incentive for financial hacking and further detaches pursuit of financial return from realization of economic return. It makes the rules less comprehensible. And it gives the politicians and regulators more to do in the markets, which makes them more attractive targets for lobbyists. He's increasing the incentives for soft corruption while making it harder to spot, the consequences are easily predicted. Cuban is a smart and pragmatic guy with billions of reasons to think himself smarter than the average bear. Part of his smarts are an ability to keep it simple, and an instinct when things are out of whack. But here that instinct have lead him through simple on to simplistic.