Tail Risk

What is ‘Tail Danger’

Tail danger is a form of portfolio risk that emerges when the possibility that an investment will move more than 3 basic discrepancies from the mean is greater than what is shown by a regular distribution. Tail risks consist of events that have a small probability of occurring and occur at the ends of a normal distribution curve.


Traditional portfolio strategies usually follow the concept that market returns follow a normal distribution. However, the idea of tail threat suggests that the circulation of returns is not regular, however manipulated, and has fatter tails. The fat tails indicate that there is a possibility, which may be little, that a financial investment will move beyond three basic deviations. Distributions that are characterized by fat tails are often seen when taking a look at hedge fund returns.

Normal Distribution

When a portfolio of financial investments is created, it is assumed that the circulation of returns will follow a normal circulation. Under this presumption, the likelihood that returns will move between the mean and three standard variances, either favorable or unfavorable, is approximately 99.97%. This implies that the likelihood of returns moving more than 3 standard variances beyond the mean is 0.03%. The presumption that market returns follow a regular distribution is crucial to lots of monetary models, such as Harry Markowitz’s contemporary portfolio theory and the Black-Scholes Merton option rates model. However, this presumption does not correctly show market returns and tail events have a large impact on market returns.

Distribution Tails

Stock exchange returns tend to follow a regular circulation that has excess kurtosis. Kurtosis is an analytical step that shows whether observed information follow a heavy or light trailed circulation in relation to the typical circulation. The regular distribution curve has a kurtosis equal to three, and for that reason, if a security follows a distribution with kurtosis higher than three, it is stated to have fat tails. A leptokurtic distribution, or heavy tailed circulation, portrays circumstances in which extreme results have actually occurred more than expected. Therefore, securities that follow this distribution have actually experienced returns that have actually exceeded three standard discrepancies beyond the mean more than 0.03% of the observed results.

Hedging Versus Tail Risk

Although tail occasions that adversely impact portfolios are uncommon, they might have large unfavorable returns. Therefore, investors should hedge against these events. Hedging against tail threat aims to boost returns over the long-term, but financiers need to assume short-term costs. Financiers might aim to diversify their portfolios to hedge against tail danger. For example, if an investor is long exchange-traded funds (ETFs) that track the Requirement & Poor’s 500 Index (S&P 500), the investor could hedge versus tail danger by buying derivatives on the Chicago Board Options Exchange (CBOE) Volatility Index, which is inversely correlated to the S&P 500.

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