“exogenous” events for securities markets: what they are


Exogenous means “coming from outside.”  In economic modelling, it means an influence that arises from outside the scope of model and that is, therefore, neither predicted nor explained by the model.

In financial markets, an exogenous event has come to mean:

–some really bad thing that occurs, which has a significant, enduring negative effect on prices, and

–one that’s outside the realm of everyday competition among firms, the cyclical rhythms of a nation’s business cycle or the interaction among countries.


The two “oil shocks” of the 1970s–both of which helped precipitate severe recessions in oil-importing countries–are the events most often cited as exogenous shocks.  Saddam Hussein’s invasion of Kuwait in 1990 is another, as is 9/11/2001.  So, too, is the near-collapse of the US financial system under the weight of dubious sub-prime mortgages.

A definitional point:  unless we’re talking about an invasion from space or a large meteor hitting the earth, no event can be exogenous for everybody.  When OPEC raised the price of oil from $1.70 a barrel to $30+, it was a bonanza for its members.  For the US and Europe, however, whose industry was deeply dependent on a steady flow of cheap petroleum products, the development was a disaster.

The sub-prime mortgage crisis was an exogenous event for the rest of the world, but an endogenous one for the US.

No one talks about the subsequent plunge of crude oil to below $10 a barrel as an exogenous event, either.  The term seems to be reserved for economic calamities that affect the large stock markets of the world.

exogenous events are predictable…

Anyone reading the founding documents of OPEC realizes that it’s a political organization, not an economic one.  It wanted justice, not monopoly profits.  And, although the full details weren’t apparent except after the fact, the production contracts between the oil majors and OPEC nations, which had sometimes been running for several decades, were extremely one-sided in the former’s favor.

…but they often come as a shock anyway…

Many times, professional investors’ focus is narrowly fixed on the domestic business cycle or the competitive interplay among firms in a given industry.  They don’t have any skill or interest in any other areas.  Experience also shows that “big picture” developments are often irrelevant for stocks.  The quality of the information generated by brokers–the biggest information channel professional investors use–about political/social topics is often very low.

…if nothing else, their timing is hard to gauge

OPEC was founded in 1960 but didn’t begin to make a significant impact on oil prices until 1970.  The roots of the sub-prime mortgage crisis can be traced back to Fed actions in 2002-2003, to G. W. Bush’s housing policy, or even to the Clinton administration.  Rampant housing speculation and sub-prime abuses were readily apparent in 2005-06.

In these cases, however, stock market consequences came much later.

being right can be a cold comfort for professionals

Any portfolio manager who adopted a very defensive posture in 2005 in anticipation of the Lehman collapse would doubtless have lost most of his clients before the event itself occurred in 2008.

In addition, one always has to calculate how the performance gained by being correct in predicting an exogenous event stacks up against the performance lost while waiting for the event to occur.  In my observation of “big picture” portfolio managers, their personal ego satisfaction is often the greatest gain they achieve.

In fact, I once had a PM who worked for me tell me that a stock bought eight years earlier, which had almost immediately dropped like a stone and was subsequently sold, hadn’t been a mistake after all.  How so?  The firm was in the process of being bought, by Warren Buffett, and at a higher price than the initial purchase.  Yes, that’s (more than) a little crazy.  But it shows how insidious cognitive dissonance can be.

That’s not to say we shouldn’t worry about exogenous events.  Quite the contrary, because they do occur.  And not all of them are complete bolts out of the blue.  But factoring them into portfolio strategy is a bit more complicated than it might seem.

the current worry

It’s Iran’s nuclear program.  More about this on Monday.




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