Enrich Your Future 18: Build a Portfolio That Can Withstand the Black Swans

By Andrew Stotz | November 8, 2024 |

The post was originally published here.

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Quick take

In this episode of Enrich Your Future, Andrew and Larry Swedroe discuss Larry’s new book, Enrich Your Future: The Keys to Successful Investing. In this series, they discuss Chapter 18: Black Swans and Fat Tails.

LEARNING: Never treat the unlikely as impossible. Diversify your portfolio to withstand black swans.

“If you build a portfolio that can withstand the black swans and is highly diversified, then psychological or economic events won’t force you to sell.”

Larry Swedroe

In this episode of Enrich Your Future, Andrew and Larry Swedroe discuss Larry’s new book, Enrich Your Future: The Keys to Successful Investing. The book is a collection of stories that Larry has developed over 30 years as the head of financial and economic research at Buckingham Wealth Partners to help investors. You can learn more about Larry’s Worst Investment Ever story on Ep645: Beware of Idiosyncratic Risks.

Larry deeply understands the world of academic research and investing, especially risk. Today, Andrew and Larry discuss Chapter 18: Black Swans and Fat Tails.

Chapter 18: Black Swans and Fat Tails

In this chapter, Larry explains the importance of never treating the unlikely as impossible and ensuring your plan includes the near certainty that black swan events will appear. Thus, your plan should consider their risks and how to address them.

Understanding the risk of fat tails

In terms of investing, Larry says, fat tails are distributions in which very low and high values are more frequent than a normal distribution predicts. In a normal distribution, the tails to the extreme left and extreme right of the mean become smaller, ultimately reaching zero occurrences.

However, the historical evidence on stock returns is that they demonstrate occurrences of low and high values that are far greater than theoretically expected by a normal distribution. Thus, understanding the risk of fat tails is essential to developing an appropriate asset allocation and investment plan. Unfortunately, Larry notes, many investors fail to account for the risks of fat tails.

History of the black swans

With the publication of Nassim Nicholas Taleb’s 2001 book Fooled by Randomness, the term black swan became part of the investment vernacular—virtually synonymous with the term fat tail. In his second book, The Black Swan, published in 2007, Taleb called a black swan an event with three attributes:

It is an outlier, as it lies outside the realm of regular expectations because nothing in the past can convincingly point to its possibility.
It carries an extreme impact.
Despite its outlier status, human nature makes us concoct explanations for its occurrence after the fact, making it explainable and predictable.

Taleb went on further to show that stock returns have big fat tails. Their distribution of returns is not normally distributed, and fat tails mean that what people think are unlikely events are much more likely to occur than people believe will.

To illustrate this, Larry uses an example: if you take stock returns, and in the last 100 years, you cut out one best month per year, which is 1% of the distribution, the assumption is that you wouldn’t lose all that much of the returns. But the fact is, you lose most of the returns. So that’s the good fat tails. Similarly, if you avoid the worst months, your returns become spectacular.

Do not try to time the market

However, Larry cautions investors that trying to time the market because of unpredictable events is the wrong strategy. The fact that you have fat tails in the data doesn’t mean you should try to time the market or engage in an active management strategy because evidence shows that it doesn’t work.

What it means, very simply put, is that your investment strategy, investment policy, and asset allocation decisions must take into account that these fat tails exist; they’re unpredictable, and therefore, don’t take more risks than you can stomach. Further, Larry adds, you must be prepared to rebalance the portfolio to take advantage of those drops and buy more when things are down.

Active management will not protect you from fat tails

The existence of fat tails doesn’t change the prudent strategy of being a passive buy, hold, and rebalance investor. Active managers have demonstrated no ability to protect investors from fat tails.

However, the existence of fat tails is significant because of their effect on portfolios. The risks of black swans and the damage they can do to portfolios, especially for those in the withdrawal phase, must be considered when designing your asset allocation. With that in mind, Larry offers the following advice:

Make sure your investment plan accounts for the existence of fat tails.
Don’t take more risks than you have the ability, willingness, or need to take.
Never treat the unlikely as impossible or the likely as certain.

Did you miss out on the previous chapters? Check them out:

Part I: How Markets Work: How Security Prices are Determined and Why It’s So Difficult to Outperform

Part II: Strategic Portfolio Decisions

About Larry Swedroe

Larry Swedroe was head of financial and economic research at Buckingham Wealth Partners. Since joining the firm in 1996, Larry has spent his time, talent, and energy educating investors on the benefits of evidence-based investing with an enthusiasm few can match.

Larry was among the first authors to publish a book that explained the science of investing in layman’s terms, “The Only Guide to a Winning Investment Strategy You’ll Ever Need.” He has authored or co-authored 18 books.

Larry’s dedication to helping others has made him a sought-after national speaker. He has made appearances on national television on various outlets.

Larry is a prolific writer, regularly contributing to multiple outlets, including AlphaArchitect, Advisor Perspectives, and Wealth Management.

Posted in Enrich Your Future, Podcast