Is the Market Rational?
Thursday, June 18, 2009 at 7:00AM by
Russ Thanks to a colleague, who wishes to remain anonymous, for the following:
Over six years ago, Fortune writer Justin Fox wrote an article titled, “Is the Market Rational?” Much of the article focused on the intellectual rivalry between two Chicago professors—Eugene Fama and Richard Thaler—and Fox made no secret which of the two he found more persuasive. The next generation of finance professors, he said, were “ripping Fama’s teachings to shreds,” and market efficiency as an organizing principle was being shouldered aside by something called “behavioral finance.” In this view, irrational investors make systematic judgment errors that produce predictable patterns in stock prices. Fox noted approvingly that the Nobel Prize in economics had been awarded the previous month to a Princeton psychology professor in recognition of his work on behavioral biases and suggested it was possible for investors with sufficient “contrarian gumption” to outperform the market by exploiting such biases. But he doubted most of his readers would be successful in this effort, due to their own propensity to make mistakes. His conclusion for investors? “That’s easy,” he wrote. “Buy and hold. Diversify. Put your money in index funds. Pay attention to the one thing you can control—costs—and keep them as low as possible.”


