Nobel Prize winners say markets are irrational, yet efficient

Are stock markets irrational, driven by greed and fear, subject to euphoria and panic? Or are they highly efficient indicators of intrinsic value? Both, says the Nobel Prize Comittee for Economics, with no sense of contradiction.

It has just awarded the prize jointly to economists with opposing views. Robert Shiller is famous for two versions of his book \’Irrational Exuberance\’. The first version appeared in 2000 at the height of the dotcom boom, and correctly predicted that this was a bubble about to burst. The second version came in 2005 just as the housing market was skyrocketing, and predicted (again correctly) that this too was a bubble likely to burst resoundingly.

This confirmed Shiller\’s status as a behavioural economist. Such economists laugh at the notion that human beings are rational economic actors, as portrayed in textbooks. No, say behaviourists, humans are driven by fads, prejudices, manias, and irrational bouts of optimism and pessimism. Yet Shiller is going to share the Nobel Prize with Eugene Fama, famous for his \”efficient markets hypothesis.\” This states that markets are like computers processing information from millions of sources on millions of economic actors, and hence produce more efficient long-run valuations than the most talented genius.

Fama\’s market behaviour is fundamentally random, so future trends cannot be predicted by even the cleverest investors. He implies that choosing stocks by throwing darts at a stock market chart can beat the recommendations of top experts. This has been verified by some, though not all, dartthrowing contests.

Corollary: ordinary investors must not pay high fees to experts to pick winners. Instead they should invest passively in a group of shares (like the 30 shares constituting the Bombay Sensex or Dow Jones Industrial Average), and ride these bandwagons without paying any fees. This has led to the spectacularly successful emergence of Index-traded funds (like those run by Vanguard in the US). Such funds are indexed to share groups like the Sensex or the Banks Nifty. Rather than try to pick individual winners in say the auto, pharma or realty sectors, index funds invest passively in a group of auto, pharma or realty companies. This has proved successful and popular.

Two groups criticize the efficient markets hypothesis: big investment gurus and, paradoxically, leftists viewing financial markets as instruments of the devil. Investment gurus like Warren Buffett in the US or Rakesh Jhunjhunwala in India claim to have beaten the market average handsomely, thus disproving the efficient markets hypothesis. Not so says Fama: in any large collection of investors there will always be some who perform above average and some below average – this is a matter of statistical chance, not skill. Moreover, investment gurus have so many contacts that they may have insider information enabling them to beat the market by unfair means.

As for Shiller\’s successful predictions, Fama says capitalism is driven by booms and busts. To predict at the height of a boom (like Shiller) that a bust will follow is banality, not genius. It is as unremarkable to predict during every bust that a boom will follow.

After the 2008 global financial crisis, the new conventional wisdom is that governments need macro prudential policies to check future financial crises, and that finance should be more strictly regulated than ever before. However, the counter is that the financial crisis occurred even though the financial sector was already the most regulated (with 12,000 regulators in the US alone). Governments had encouraged reckless lending by guaranteeing large banks and investment banks against failure, and by creating government backed underwriters like Fannie Mae who shouldered any burdens caused by mass default.

Perhaps the Nobel Prize Committee is right in implying that markets can be both irrational and efficient at the same time. Since humans are irrational, they will always create markets that have booms and busts, marked by irrational optimism and pessimism. An efficient markets defined by Fama and his followers is not one that produces steady growth without booms, busts or crises. It is efficient only in the limited sense that, whether the markets are calm or irrational, they represent the processed information of millions of actions of millions of actors, and this is inherently more efficient than the efforts of any individual investor.

The argument is analogous to the one against communism or dictatorship. Communists believed that the great and good politburo, motivated entirely by the public interest and not profit, would run the economy better than the chaos, irrationality and imperfections of the capitalist market. Yet the market, with all its flaws and irrationality, proved infinitely more efficient.

Fama holds that this is true of financial markets too. This is compatible with Shiller\’s analysis. Markets can be both irrational and efficient.

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