But what exactly is the output of the financial services sector? [...] If one investment fund is outperforming another through picking the right shares, is not another fund losing on the other side of the equation? What makes it a positive-sum rather than a zero-sum business? [...] "Common sense suggests that if a closed circle of people continuously exchange bits of paper with each other, the total value of these bits of paper will not change much, if at all. If some members of that closed circle make extraordinary profits, these profits can only be made at the expense of other members of the same circle." [...]