Investing is no monkey business

In the debate of passive v.s. active investing, the proponents of index funds often refer to the famous chimpanzee experiment, where a chimp picks stocks by tossing coins on Wall Street Journal and out performs half of the mutual fund managers (in this book, for example). As much as I believe in the Efficient Market Hypothesis --- at least in its weak form and partly the semi-strong form --- I'd have to say that this argument is invalid. It's just like asking a two year old to draw one piece of paper from a stack of graded college exams, then claim the child can beat half of the students in that exam. The market is built by the professional money managers in the first place. The chimp simply gets the luxury of efficiency already in existence. A truely valid test would be to host a zoo of chimpanzees, let them "pick" stocks as they wish and actually trade following these pickings in the order size an average money manager trades. I bet our chimps will be exploited down to their underpants --- if they ever had one. Market being efficient or not, investing is no monkey business.