Tail risk of contagious diseases

Pasquale Cirillo & Nassim Nicholas Taleb

The COVID-19 pandemic has been a sobering reminder of the extensive damage brought about by epidemics, phenomena that play a vivid role in our collective memory, and that have long been identified as significant sources of risk for humanity. The use of increasingly sophisticated mathematical and computational models for the spreading and the implications of epidemics should, in principle, provide policy- and decision-makers with a greater situational awareness regarding their potential risk. Yet most of those models ignore the tail risk of contagious diseases, use point forecasts, and the reliability of their parameters is rarely questioned and incorporated in the projections. We argue that a natural and empirically correct framework for assessing (and managing) the real risk of pandemics is provided by extreme value theory (EVT), an approach that has historically been developed to treat phenomena in which extremes (maxima or minima) and not averages play the role of the protagonist, being the fundamental source of risk. By analysing data for pandemic outbreaks spanning over the past 2500 years, we show that the related distribution of fatalities is strongly fat-tailed, suggesting a tail risk that is unfortunately largely ignored in common epidemiological models. We use a dual distribution method, combined with EVT, to extract information from the data that is not immediately available to inspection. To check the robustness of our conclusions, we stress our data to account for the imprecision in historical reporting. We argue that our findings have significant implications, including on the extent to which compartmental epidemiological models and similar approaches can be relied upon for making policy decisions.

Link to the Paper – Tail risk of contagious diseases

Bloomberg: Black Swan Author Spars With Quant Legend Over Tail Risk Hedges

“Black Swan” author Nassim Nicholas Taleb and quant investing pioneer Cliff Asness have engaged in a vitriolic Twitter dispute over the esoteric world of tail-risk hedging that descended into personal insults.

The spat began when Taleb sent a pair of tweets accusing the $143 billion AQR Capital Management LLC of issuing flawed reports that say tail-risk hedging doesn’t work.

Link to Bloomberg article: Black Swan Author Spars With Quant Legend Over Tail Risk Hedges

[YouTube] Tutorial: Simple Trick to see the effect of Power Laws

A simple tutorial explaining how in the presence of power laws (with low exponent) most of the body of the distribution becomes noise. Once you establish that a variable is in the power-law class, some necessary consequences come out. To debunk that history is dominated by tail events, you must show it does not follow a power law.

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The only man who has a clue about the Coronavirus Pandemic

Link to original article – Taleb: The Only Man Who Has A Clue

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Bloomberg: Nassim-Advised Universa Tail Fund Returned 3,600% in March

A tail-risk hedge fund advised by Nassim Taleb, author of “The Black Swan,” returned 3,612% in March, paying off massively for clients who invested in it as protection against a plunge in stock prices

The fund, managed by Universa Investments of Miami, had a year-to-date return of 4,144% through the end of last month, according to an investor letter from President and Chief Investment Officer Mark Spitznagel that was obtained by Bloomberg. He said Universa was able to cash in many of its positions, locking in the gains, while also keeping in place protection against more equity sell-offs, “one of the tricks of the trade.”.

Link to Bloomberg article: Nassim Taleb-Advised Universa Tail Fund Returned 3,600% in March

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Bloomberg: Portfolios to ‘Blow Up’ Without Tail Hedges

“The worst thing you can do with insurance is try to time it,” Taleb, a distinguished professor of risk engineering at New York University, said in an interview Monday on Bloomberg Television. “If you don’t have tail insurance, you don’t have a portfolio. Your portfolio is going to blow up.”

That’s a sobering reality check from someone who has long argued that instead of turning to the government for help in times of crisis, big investors and corporations should manage their own risks. His pleas for prudence were largely ignored, though, and most parts of the economy were ill-prepared for a sudden downturn when the coronavirus hit.

Link to Bloomberg article: Taleb Says Portfolios to ‘Blow Up’ Without Tail Hedges

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The book Statistical Consequences of Fat Tails: Real World Preasymptotics, Epistemology, and Applications is finally on Amazon

Cover of Nassim's book

The book Statistical Consequences of Fat Tails: Real World Preasymptotics, Epistemology, and Applications is finally on Amazon. Click Here.

PDF freely available here – Nassim Nicholas Taleb (2020). Statistical Consequences of Fat Tails: Real World Preasymptotics, Epistemology, and Applications. RESEARCHERS.ONE, https://www.researchers.one/article/2020-01-21.