How should speculation be controlled in a free market?

There isn't an easy answer to speculation because it all part of what makes capitalism work.. greed greed greed and more greed by those who have and want more while those who have little get less. I suppose that the only way to stop speculation would be to close all the commodity markets trading houses and stock exchanges around the world. which would lead to a collapse of the financial banking systems and absolute ruin for every economy around the world .