The sale of “borrowed” stocks without registering this borrowing nor even informing the “lender” is in my mind an impropriety and should be outlawed or heavily taxed to discourage it. I’m quite sure Obummer has this practice in his target to discourage with heavy fines in the future.
Similarly, the investment in commodities in which one has no intention of taking delivery of nor even the capability of using such commodity should be outlawed. “Making” these markets is a sham whose only objective it to cause prices to rise.