Book Review: Fooled by Randomness

Nassim Nicholas Taleb’s book should come with a warning on the cover: “If you are turned off by an arrogant, attacking, argumentative style, you will miss one of the best set of ideas on markets and investing in the last 20 years.”[1]

Now that I have given you, slyly, the same warning, let me emphasize the second part of my warning, because this book rewards the effort.

As in its successor, The Black Swan: The Impact of the Highly Improbable, Taleb tears down unexamined assumptions about the patterns we see in the world.  Similarly, Fooled by Randomness
hews to my preferred ‘How NOT To Invest’ rule on useful finance books, rather than the more typical airport bookstore “How To Invest” books that make me want to gag.

Taleb’s writing usefully addresses the question: When you consider investing in a successful money manager, posting consistently high returns over an impressive number of years, is that a brilliant investor or just the result of dumb luck?

Taleb walks the reader through a coin toss experiment which – for me at least – demolishes the typical treatment of the Financial Infotainment Industrial Complex’s celebration of “money manager brilliance,” in one clean hypothetical example.

Take 10,000 money managers, each of whom has a 50% probability of making $10K in a year, and a 50% probability of losing $10K in a year.  Any manager who loses $10K in a year gets tossed out of the pool of remaining managers.

At the end of the year, we expect approximately 5,000 money managers will be up $10K , while 5,000 money managers will permanently leave the pool of money managers.

When we run the game for a second year, 2,500 managers remain, each of whom has had a string of 2 good ‘up’ years.  After three years we have 1,250 managers, after four years we have 625 managers, and after five years we have 313 managers.  In Taleb’s experiment, these 313 managers have managed to post 5 brilliant years in a row, (with no down years!), although we know this is due to the pure dumb luck of the experiment.

As Taleb points out, and we know instinctively from the way the Financial Infotainment Industrial Complex works, these lucky 5-year managers will be hailed for their incisive minds, their vigorous yoga regimen, or their humble and strict upbringing.  If they then stumble in the next year, the Financial Infotainment Industrial Complex will point to the outdated approach of their investment thesis or the moral dissipations of their early success.  Or whatever.  The real truth is, as Taleb says, their luck changed more than they changed.

From a random dumb-luck cohort of investment managers, we can produce, consistently, a number of successful winners (3% in his example, over 5 years) who will receive undeserved accolades, even as their success appears to show a non-random seeming, statistically improbable, string of successes.

It’s easy to parody Taleb’s argument as ‘it’s all luck,’ but it’s more difficult, and more profitable, to examine ways in our own personal and financial lives in which we ascribe too much causality to random events and random markets.

In the simplest but most profound sense, about 99%[2] of the conversations I have or hear about investing, even (especially!) among serious people, invoke causality instead of luck, and see patterns instead of randomness.  We say the word ‘investing’ but we really mean, unknowingly, ‘gambling.’

A few other reasons I like Fooled by Randomness:

  1. I love the section midway through Fooled by Randomness in which Taleb describes the successful and personable “Carlos,” an emerging markets bond trader who, throughout a number of years, made $80 million for his bank, with nary a down quarter, only to blow a $300 million hole in his firm’s balance sheet during one traumatic summer of 1998 featuring the blowout of swap spreads, The Russian bond default, and the implosion of Long Term Capital Management.  Since I lived and breathed that market, and those years, with bond trading colleagues just like Carlos, I can relate.
  2. I serve as a fiduciary for a school whose endowment matters tremendously for the operation of the institution.  One of the never-ending challenges for any fiduciary who shares Taleb’s empirical skepticism is to keep returning to the role of luck and randomness in short and medium-term investment returns.  We want to be smart, but part of being smart, according to Taleb, is acknowledging that luck and randomness account far more for success than we prefer to believe.  We receive quarterly investment returns from our managers, but the value of that information is nearly zero.  It’s just noise.  As a natural corollary, decisions about money managers based on relatively short-term investment results should be made with a healthy dollop of skepticism.


Finally, one of the joys of Taleb is that he and his ideas engage productively in a dialogue with other thinkers.  Nate Silver’s The Signal and the Noise followed Fooled By Randomness in time but helps build a similar helpful skepticism about what we can know and not know from observable data and phenomenon.  The human tendency to see patterns and ascribe causality where none exists can be usefully counteracted through their thinking.

Taleb also explicitly attacks, among numerous others, a book I admire, Thomas Stanley’s The Millionaire Next Door.[3]  Taleb argues, correctly, that Stanley’s methodology crumbles in the face of statistical logic.[4]  I agree with Taleb on the statistical critique, while I also believe in Stanley’s conclusions and advice on how to conduct one’s personal and financial life.

One can be right for the wrong reasons, as well as wrong for all the right reasons, as I imagine Taleb would heartily agree.


Please also see my review of Nicholas Nassim Taleb’s Black Swan.

Please also see my review of Thomas Stanley’s The Millionaire Next Door

Please see related post: All Bankers Anonymous Book Reviews in one place.

[1] I read Fooled by Randomness when it first came out in 2005.  Since then I’ve often reflected on how difficult a job Taleb’s editor must have had.  Given the final product, earlier drafts must have been even more outrageously full of slashing critiques of all the idiots and frauds Taleb perceives everywhere.  In the forward to the second edition, Taleb acknowledges both his slashing style and his editor’s attempts to tone him down.  True to form, he argues his idiosyncratic style makes for better reading.  In a weird way, I agree.  But at least you’re now forwarned.

[2] I’m rounding down, to be conservative.

[3] I’ll review that one on this site soon.

[4] Stanley attempts to draw conclusions about ‘how to be millionaire’ based on surveys of millionaires.  His first problem is that he’s only interviewing a sample of millionaire ‘winners,’ so we really cannot know how many people followed the same exact path but ended up ‘losers.’  He has a flawed survivorship bias – similar to observing the universe of hedge fund managers today and drawing conclusions about the merits of hedge fund investing without taking into account the funds that did not survive.  Second, Taleb points out that the time period covered by Stanley’s study was a particular financial and economic moment in time of bull markets and asset price inflation.  A different time period might lead to an entirely different set of conclusions about ‘how to be a millionaire.’

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8 Replies to “Book Review: Fooled by Randomness”

    1. Is that what Taleb suggested? It hoguht it was more to do the barbell strategy of 80% of your wealth in ultra low risk and the rest in ultra high risk geared toward waiting for a black swan.

      1. Taleb and his partners do have an investment strategy, which you can read about online, that tries to capture the upside of unexpected volatility.
        But his books really don’t talk about ‘how to invest,’ but rather ‘how to think,’ and possibly, by extension, how to not make big investment errors that we all commonly make.

  1. Hey, I’m a new reader and really enjoy your blog! I fully agree with your review of Fooled by Randomness and actually liked it more than his other 2 books.

    My question for you is how do you recommend a person should invest. What should I be doing as opposed to what should I not be doing? Can an individual actually beat the market in your opinion or is it all pure chance?

    1. Thanks for reading, and for your nice comment. As for your question of how you, or another person, should invest: Answering that would involve knowing lots more about your particular situation.
      I’m sure, however, you shouldn’t take advice from some online guy who calls himself ‘Mike the Anonymous Banker’ 🙂
      Despite that caveat, I think your, or anyone’s, investment approach should focus on choosing how to best participate in the market rather than ‘beating the market.’
      99.5% (I’m rounding downward) of the financial infotainment industrial complex wants to tell you how you should ‘beat the market,’ but I believe that really shouldn’t be the goal.
      A roughly equivalent % of the financial infotainment industrial complex will never ‘beat the market,’ so they are delusional at best, and mostly disingenuous.

  2. Let me have a crack at answering James’s question – before you walk, you need to crawl. Start by learning how to read financial statements (balance sheet, income statement, statement of cash flow). Without a firm understanding of these three simple reports, your chances of success are greatly limited.

  3. I really enjoyed Fooled by Randomness, but thought that the potshots taken at The Millionaire Next Door were a bit odd.

    Even if The Millionaire’s methodology didn’t meet statistical rigor and suffered from selection bias, the behavior of the various subjects interviewed matched the pattern of Taleb’s hypothetical Manhattan dentist who is probabilistically richer than any lottery winner. I think the exact quote was something like “out of all the possible universes, the lottery winner lives in poverty in most of them, whereas the dentist is happily drilling teeth and making money in most”.

    Logic would dictate that living within one’s means and investing regularly would make one probabilistically richer than someone who doesn’t, no?

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I founded Bankers Anonymous because, as a recovering banker, I believe that the gap between the financial world as I know it and the public discourse about finance is more than just a problem for a family trying to balance their checkbook, or politicians trying to score points over next year’s budget – it is a weakness of our civil society. For reals. It’s also really fun for me.

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