Seriously People, It's Time To Stop Talking About Black Swans

It has become highly fashionable to talk about “black swans” since the crisis began in 2008 and now even Scott Sumner has talked about it in his recent post “Don’t forget about those black swans.” 

Scott’s headline reminded me how much focus there is on “black swans” these days – especially among central bankers and regulators and to some extent also among market participants.

What is a black swan? The black swan theory was popularised by Nassim Taleb in his 2007 book “The Black Swan.” 

Taleb’s thesis is basically that financial markets under-price the risk of extreme events happening. Taleb obviously felt vindicated when the crisis hit in 2008. The extreme event happened and it had clearly not been priced by the market in advance.

Lets go back to to Scott’s post. Here he quotes Matt Yglesias:

Here’s a fun Intrade price anomaly that showed up this morning. The markets indicate that there’s more than a 3 per cent chance that neither Barack Obama nor Mitt Romney will win the presidential election. That’s clearly way too high.

Scott then counters Matt by saying that we should not forget about “something unusual happening”:

1.  One of the two major candidates is assassinated, and the replacement is elected (as in Mexico’s 1994 election.)

2.  Ditto, except instead of assassination one candidate pulls out due to health problems, or scandal.

3.  A third party candidate comes out of nowhere and gets elected.

Scott is of course right. All this could happen and as a consequence it would obviously be wrong if the market had priced a 100% chance that nobody other than Obama or Romney would become president.

Scott and I tend to think that financial markets are (more or less) efficient and as a consequence we would not be gambling men. Scott nonetheless seem to think that the odds are good:

“But 3% is low odds.  It’s basically saying once in every 130 years you’d expect something really weird to happen in US presidential politics during an election year.   That’s a long time!  Given all the weird things that have happened, how unlikely is it?  Some might counter that none of the three scenarios I’ve outlined have occurred in the U.S. during an election year (my history is weak so I’m not certain.)  But mind-bogglingly unusual things have happened on occasion.  On November 10, 1972, what kind of odds would Intrade have given on neither Nixon nor Agnew being President on January 1, 1975?”

Scott certainly has a good point, but I will not question the market on this one. Market pricing is the best assessment of risk we have. Obviously Taleb disagrees as he believes that markets tend to underprice risk. However, I fundamentally think that Taleb is wrong and I don’t see much evidence that markets underprice black swan events. The fact that rare events happen is not evidence that the market on average underprices the likelihood of these events.

The long-shot bias and central banks
In the evidence from betting markets it seems to indicate that if anything bettors tend to have a favourite-longshot bias meaning that they tend to over-price the likelihood that the favourite will lose elections or sport games. Said in another way if anything bettors tend to over-price the likelihood of black swan events. I happen to think that this is not a problem for markets in general, but it nonetheless indicates that if anything the problem is too much focus on black swan events rather than too little focus on them.

This to a very large extent has been the case for the past 4 years – especially in regard to central banking and banking regulation. There seems to be a near-obsession among some policy makers that a new black swan could turn up. How often have we heard the talk about the major risk of bubbles if interest rates are kept too low too long? Most of the new financial regulation being pushed through across the world these days is justified by reference to the risk of some kind of black swan event.

Media and policy makers in my view have become obsessed with extreme events happening – you will be reminded about that every time you go through the security check in any airport in the world.

The obsession with black swan events is highly problematic as the cost of policy makers obsessing about very unlikely events happening leads them to implement very costly regulation that leads to massive waste of resources.

Again just think about how many hours you have spent waiting to get through airport security over the last couple of years and if you think that is bad just think of the cost resulting from excessive new regulation of the global financial markets.

So my suggestion is clearly to forget about those black swans!


Finally here are three book recommendations on the subject:

Risk by Dan Gardner that tells about the “politics of fear” (of black swans).

The Myth of the Rational Voter by Bryan Caplan explains why democracy tends to lead to irrationality while markets lead to rationality. Said in another way policy makers would be more prone to focus on black swans than market participants in free markets would be.

Risk, Uncertain and Profit – Frank Knight’s classic. If you are really interested in the issues of risk and uncertainty then there is no reason at all to read Taleb’s books (I have read both The Black Swan and Fooled by Randomness – they are “fun” and something you can read while you are waiting in line at the security check in the airport, but it is certainly not Nobel prize material).

Instead just read Knight’s classic. It is much more insightful. It is actually something that frustrates me a great deal about Taleb’s books – there is really nothing new in what he is saying, but he claims to have come up with everything himself.

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