On The Wisdom Of Crowds (And Madness Of Mobs)

Tyler Durden's picture

Fear, like greed, makes people, and that would include investors, behave irrationally. Two major equity bear markets in the last 13 years have traumatized investors. The belief in Modern Portfolio Theory in general and the Efficient Markets Hypothesis (EMH) in particular has been shaken and finance theory will have to be re-written. So, Absolute Return Partners' Niels Jensen asks, what is it specifically that has changed? Human behavior certainly hasn’t. Greed and fear have been factors to be reckoned with since day nought. When faced with the unknown, people (in this case, fund managers) will use whatever information they can get hold of. Hence we shouldn’t really be surprised that fund managers extrapolate current earnings trends when forecasting future earnings, despite the evidence that it is a futile exercise. Occasionally, the Wisdom of Crowds turns into the Madness of Mobs and all rational behavior goes out the window. History provides many examples of that. EMH is entirely unsuited to deal with froth. What made economists love the EMH is that the maths behind it is so neat whereas the alternative truth is a little messy.

 

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The new paradigm

Two major equity bear markets in the last 13 years have traumatised investors. The belief in MPT in general and EMH in particular has been shaken and finance theory will have to be re-written, or so it looks. So what is it specifically that has changed? Human behaviour certainly hasn’t. Greed and fear have been factors to be reckoned with since day nought. Dr. Lo, who has pioneered the research into how EMH can be adapted to incorporate behavioural factors, offers the following explanation (and I paraphrase):

The growing importance of the financial services industry, together with geopolitical changes (the U.S. is no longer the only dominant economic force in the global economy), and rapid advances in technology, have destabilised the equilibrium. The obvious implication, or so Dr. Lo argues, is that investors must change some of the tools in their tool box.

Interestingly, he doesn’t suggest that EMH should be mothballed altogether. To the contrary, he believes that EMH can work for extended periods of time provided investors behave rationally. I had the pleasure of meeting him in Cambridge (Massachusetts) a few weeks ago, and he delivered a convincing case that investor behaviour is actually rational most of the time when looked upon in aggregate. He calls it the Wisdom of Crowds and illustrated what he means with a simple example:

Imagine somebody puts a large jar full of jelly beans in front of you and you are meant to guess how many jelly beans the jar contains. You have no idea, but you are up for it, so you come up with a number. Sadly, unless you happen to be lucky, the chances are that your guess is miles off the true number. Now imagine that the same question is put to a large number of people and that the mean is calculated as the simple average of all the estimates. Interestingly, research suggests that the mean estimate is likely to be within a few percentage points of the true number. The Wisdom of Crowds.

The FT ran a story at the height of the credit boom back in April 2006 on the rapid growth of the CDO market in Europe. When asked by the FT to
comment on this remarkable growth, Cian O’Carroll, European head of
structured products at Fortis Investments, replied:

“You buy an AA-rated corporate bond you get paid Libor plus 20 basis points; you buy an AA-rated CDO and you get Libor plus 110 basis points.”

On the back of this statement, and despite all the evidence of froth in financial markets in 2005-07, it seems like the crowd was still quite wise. As Dr. Lo states in his 2011 paper:

“It may not have been the disciples of the Efficient Markets Hypothesis that were misled during these frothy times, but more likely those who were convinced they had discovered a free lunch.”

Occasionally, the Wisdom of Crowds turns into the Madness of Mobs and all rational behaviour goes out the window. History provides many examples of that - from the tulip mania in the Netherlands in the 17th century to the more recent bubbles we have experienced in dot com stocks and housing markets around the world. The once golden boy of central banking, Alan Greenspan, labelled it irrational exuberance in a speech in 1996 when commenting on what already then looked like lofty P/E levels on U.S. equities. As we now know, the bull market not only continued for a further 3 ½ years; it actually grew stronger. Once the mob gets going, it takes a great deal to stop it.

EMH is entirely unsuited to deal with froth. Charlie Munger (of Berkshire Hathaway fame) once said, and I paraphrase, what made economists love the EMH is that the maths behind it is so neat whereas the alternative truth is a little messy.

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