How much blood can you suck out of an entire country?
University of Missouri economic historian and former Wall Street economist Michael Hudson explains, his job on Wall Street was to be the balance and payments economist for Chase Manhattan Bank. His first job there was to calculate how much debt third world countries could pay, and the answer was, "‘Well, how much do they earn?’ And whatever they earned, that’s what they could afford to pay in interest. And our objective was to take the entire earnings of a third world country and say, ‘Ideally, that would be all paid as interest to us.’” 
National and international trade have had benefited many albeit with a few problems well worth our attention. With deregulation and globalization, however, the finance industry has become deadly, reminiscent of the death toll of wars and plagues.
Today, Wall Street is less constrained. In terms of harm done and number affected, our finance industry leads the continuing war of conquest.