The Most Misunderstood Metric in Finance
The Paradox of Volatility
Few words in investing trigger as much confusion as volatility. It’s the measure of how much an asset’s returns swing over time. It’s simple and omnipresent yet often criticized as a flawed gauge of what truly keeps investors awake at night: the chance of losing money.
Despite volatility’s many theoretical shortcomings, it remains dominant for two intertwined reasons:
Everyone understands it and it’s easy to calculate.
In summary it is a remarkably effective substitute for downside risk that investors are actually concerned about.
How Volatility Became the Language of Risk
Volatility has its roots in Harry Markowitz’s pioneering work in the 1950s, which defined portfolio risk as the variance of returns. The simplicity of this approach, combined with its mathematical convenience, made volatility the cornerstone of modern portfolio theory.
But it’s not without issues:
Equal treatment of gains and losses: Investors celebrate upside moves but dread downside ones — volatility treats both the same.
Assumption of normality: The idea that returns are neatly distributed around an average is far from reality.
Even Markowitz recognized its limits. He noted that semideviation, measuring only the negative swings, would better reflect what investors truly fear. The problem back then was computing power. Variance was easy; semideviation wasn’t.
Fast forward to today, computing power isn’t a problem anymore but even with today’s advanced analytics, volatility remains a dominant yardstick. Why? Because it’s simple, universal and it gets the job done (more on that later).
The Core Issue: Volatility vs. True Risk
The fundamental challenge lies in distinguishing volatility from true risk. Volatility treats all deviations from the mean identically, meaning a 10% gain and a 10% loss both count as “risky”. For investors, that’s nonsense — no one loses sleep over a rally.
Despite this conceptual mismatch, empirical data shows that volatility often serves as a practical proxy for downside risk. When assets are ranked according to volatility, the ordering tends to mirror rankings based on pure downside measures.
Empirical analysis supports this overlap: Spearman rank correlations between volatility and alternative risk measures are typically high, underscoring the strong alignment between these two dimensions of risk. Table 1 shows the Spearman rank correlations.
Rankings of assets by volatility typically align closely with those generated from direct downside risk measures, highlighting the tight relationship between volatility and downside risk.
Conclusion
Volatility is an imperfect measure. It doesn’t distinguish “good” volatility from bad and it assumes normal distribution. But for what it’s meant to do — compare risk across assets — it remains a remarkably efficient proxy.
Volatility’s ubiquity stems not from laziness, but from its practical truth:
It’s the rare case where simplicity and accuracy overlap.
The average investor doesn’t need seven formulas or complex mathematics to understand that a stock with double the volatility is roughly twice as risky. Volatility might be blunt, but it’s directionally correct and that’s often enough.
Although often criticized, volatility continues to serve as a dependable and efficient stand-in for downside risk. Its strong correlation with adverse return outcomes makes it a credible core metric for most investors’ risk assessments.
In essence, volatility might not be perfect, but it gets the job better done than any other risk metric if you compare output and effort.
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Disclaimer
The above article constitutes my or the authors’ personal views and is for entertainment purposes only. It is not to be construed as financial advice in any shape or form. Please do your own research and seek your own advice from a qualified financial advisor. I / The authors may from time to time hold positions in the aforementioned securities consistent with the views and opinions expressed in this article. The information provided in this article is not making promises, or guarantees regarding the accuracy of information supplied, nor that you guarantee for the completeness of the information here. The information in this article is opinion-based and that these opinions do not reflect the ideas, ideologies, or points of view of any organization the authors may be potentially affiliated with. The authors reserve the right to change the content of this blog or the above article. The performance represented is historical and that past performance is not a reliable indicator of future results and investors may not recover the full amount invested.