[Deutsche Bank trader Greg] Lippman had at least one good reason for not putting up a huge fight [against the request from management to make a bet against the subprime bond market]: There was a fantastically profitable market waiting to be created. Financial markets are a collection of arguments. The less transparent the market and the more complicated the securities, the more money the trading desks at big Wall Street firms can make from the argument. The constant argument over the value of the shares of some major publicly traded company has very little value, as both buyer and seller can see the fair price of the stock on the ticker, and the broker’s commission has been driven down by competition. The argument over the value of credit default swaps on subprime mortgage bonds – a complex security whose value was derived from that of another complex security – could be a gold mine.