The asymmetry of returns is the statistical and practical property of an investment strategy or portfolio in which gains and losses are not distributed symmetrically. When the distribution of returns is positively asymmetric (right-skewed), large gains are more likely than large losses — and the occasional outsized winner more than compensates for the frequent smaller losses. When the distribution is negatively asymmetric (left-skewed), the opposite is true: large losses are more likely than large gains, making the strategy treacherous despite potentially attractive average returns.

Why Skewness Matters

Standard investment metrics — mean return, standard deviation — do not capture skewness. Two strategies can have identical average returns and identical standard deviations but completely different skewness profiles. The one with positive skewness regularly produces small losses and occasional large gains — a profile that is psychologically manageable and financially favorable over time. The one with negative skewness regularly produces small gains and occasional large losses — the profile of strategies like selling uncovered options, which appear profitable most of the time but are vulnerable to catastrophic losses when extreme events occur.

Building Positive Return Asymmetry

Creating a positively asymmetric return distribution requires systematic loss management: setting maximum loss limits, exiting losing positions promptly, and allowing winning positions to develop without premature exits. Trend-following approaches naturally produce positive skewness: they produce many small losses (false trend signals) and occasional large gains (major trend moves). This positive skewness is valuable over time even if the win rate is below 50%.

The Compound Effect of Positive Skewness

Over long periods, positive skewness in returns compares favorably with negative skewness at identical arithmetic mean returns. The geometric mean return — the actual compound growth rate — is significantly higher for positively skewed distributions. This is because positive skewness protects against the large losses that create the most damage to compounding — losses from which recovery may take years and require gains far in excess of the original decline.

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