Bernie Sanders has an interesting idea based on some research done by economist. He calls it the "Robin Hood Tax". Essentially you charge a small fee whenever

Bernie Sanders has an interesting idea based on some research done by economist. He calls it the "Robin Hood Tax". Essentially you charge a small fee whenever any trade happens in the market. The opponents of this idea state that it will prevent the market from being efficient as trading would slow down - undermining the Efficient Market Hypothesis. However his argument is that a small enough charge will not prevent genuine investor from trading and just discourage the speculative traders.