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Cognitive Biases

Bull and Bear Zoology

The terms 'bullish' and 'bearish' oversimplify market outlooks by ignoring asymmetric outcomes. A situation can be bullish in probability (70% chance of a 1% gain) but bearish in expectation due to a low probability of a large loss (30% chance of a 10% decline), illustrating the importance of considering both probability and magnitude.

THE IDEA

BULL AND BEAR ZOOLOGY

The general press floods us with concepts like bullish and bearish which refer to the effect of higher (bullish) or lower (bearish) prices in the financial markets. But also we hear people saying “I am bullish on Johnny” or “I am bearish on that guy Nassim in the back who seems incomprehensible to me,” to denote the belief in the likelihood of someone’s rise in life. I have to say that bullish or bearish are often hollow words with no application in a world of randomness—particularly if such a world, like ours, presents asymmetric outcomes.

When I was in the employment of the New York office of a large investment house, I was subjected on occasions to the harrying weekly “discussion meeting,” which gathered most professionals of the New York trading room. I do not conceal that I was not fond of such gatherings, and not only because they cut into my gym time. While the meetings included traders, that is, people who are judged on their numerical performance, it was mostly a forum for salespeople (people capable of charming customers), and the category of entertainers called Wall Street “economists” or “strategists,” who make pronouncements on the fate of the markets, but do not engage in any form of risk taking, thus having their success dependent on rhetoric rather than actually testable facts. During the discussion, people were supposed to present their opinions on the state of the world. To me, the meeting was pure intellectual pollution. Everyone had a story, a theory, and insights that they wanted others to share. I resent the person who, without having done much homework in libraries, thinks that he is onto something rather original and insightful on a given subject matter (and I respect people with scientific minds, like my friend Stan Jonas, who feel compelled to spend their nights reading wholesale on a subject matter, trying to figure out what was done on the subject by others before emitting an opinion—would the reader listen to the opinion of a doctor who does not read medical papers?).

I have to confess that my optimal strategy (to soothe my boredom and allergy to confident platitudes) was to speak as much as I could, while totally avoiding listening to other people’s replies by trying to solve equations in my head. Speaking too much would help me clarify my mind, and, with a little bit of luck, I would not be “invited” back (that is, forced to attend) the following week.

I was once asked in one of those meetings to express my views on the stock market. I stated, not without a modicum of pomp, that I believed that the market would go slightly up over the next week with a high probability. How high? “About 70%.” Clearly, that was a very strong opinion. But then someone interjected, “But, Nassim, you just boasted being short a very large quantity of SP500 futures, making a bet that the market would go down. What made you change your mind?” “I did not change my mind! I have a lot of faith in my bet! [Audience laughing.] As a matter of fact I now feel like selling even more!” The other employees in the room seemed utterly confused. “Are you bullish or are you bearish?” I was asked by the strategist. I replied that I could not understand the words bullish and bearish outside of their purely zoological consideration. Just as with events A and B in the preceding example, my opinion was that the market was more likely to go up (“I would be bullish”), but that it was preferable to short it (“I would be bearish”), because, in the event of its going down, it could go down a lot. Suddenly, the few traders in the room understood my opinion and started voicing similar opinions. And I was not forced to come back to the following discussion.

Let us assume that the reader shared my opinion, that the market over the next week had a 70% probability of going up and 30% probability of going down. However, let us say that it would go up by 1% on average, while it could go down by an average of 10%. What would the reader do? Is the reader bullish or bearish?

When to use it

  • Evaluating investment opportunities where the probability of a small gain is high but the tail risk of a large loss exists.

  • Deciding whether to purchase insurance, which has a high probability of small loss (premium) but covers a low-probability catastrophic loss.

  • Negotiating contracts with asymmetric payoff structures, such as fixed fees vs. performance bonuses.

  • Assessing scientific hypotheses where a high-probability small effect might be less important than a low-probability but revolutionary discovery.

FROM THEORY TO EVERYDAY LIFE

In practice

01

Taleb's Trading Desk Example

During a meeting at an investment bank, Nassim Taleb stated he believed the market had a 70% chance of going up, yet he was short (betting on a decline) because he expected the downside move to be much larger in magnitude. Probability-based bullishness differs from expectation-based bearishness.

02

The 70/30 Asymmetric Bet

Consider a market with a 70% probability of a 1% gain and a 30% probability of a 10% loss. The expected value is negative: (0.7 * 1%) + (0.3 * -10%) = -2.3%. Despite the high probability of a small gain, the bet is not favorable, showing that being 'bullish' in probability does not imply a bullish expectation.

✳

A MOMENT TO REFLECT

Put it to work.

  1. In what other domains might a high-probability small positive outcome be overshadowed by a low-probability large negative outcome?

  2. How can you adjust your decision-making to account for asymmetric outcomes when receiving advice or forecasts?

  3. Think of a personal or professional decision where you focused only on the most likely outcome but ignored the magnitude of possible extreme outcomes. How would reconsidering asymmetry change your choice?

CONTINUE THE CONVERSATION

Source texts

  • Fooled by Randomness The Hidden Role of Chance in the Markets and in Life (Nassim Nicholas Taleb)
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