Volatility
Definition
Volatility is a measure of how much the returns of an investment vary over time. In finance, it is typically expressed as the annualised standard deviation of periodic returns. Higher volatility means returns are less predictable and more dispersed; lower volatility means they are more consistent.
Annualised volatility = standard deviation of periodic returns x square root of the number of periods per year
For daily returns: multiply the daily standard deviation by the square root of 252 (approximate trading days per year). For monthly returns: multiply by the square root of 12.
Realised vs Reported Volatility
A critical distinction in alternatives is between realised volatility — the actual economic variability of underlying assets — and reported volatility — what appears in fund return series.
For listed assets (public equities, exchange-traded commodities, liquid hedge funds), reported volatility closely tracks realised volatility, because prices update continuously in the market.
For private market assets (private equity, private credit, infrastructure, real estate), reported volatility is based on infrequent valuations — quarterly or even annually. The gap between valuation dates means daily price movements are not observed. The result is a reported volatility that is systematically lower than the true economic variability of the assets.
Why this matters: Institutional investors using reported volatility in portfolio construction or risk models will understate the risk contribution of private market allocations. Two assets with the same underlying economic risk will appear to have very different volatility simply because one is marked daily and the other quarterly. See Valuation Risk and NAV.
Volatility Across Alternative Asset Classes
| Asset Class | Reported Volatility | Nature of the Measurement |
|---|---|---|
| Hedge funds (liquid strategies) | Moderate to high | From frequent marks; more accurate but strategy-dependent |
| Private equity | Appears very low | Quarterly NAV based on model valuations; heavily smoothed |
| Private credit | Appears low | Mark-to-model; rarely reflects secondary market volatility |
| Real estate (non-listed) | Appears low | Annual or quarterly appraisals; appraisal-smoothing effect |
| Commodities | High | Actively traded at spot prices; real-time data |
| Digital assets | Very high | Actively traded 24/7; extreme intraday and inter-period swings |
The key point: private market assets appear low-volatility primarily because they are valued infrequently. The underlying economic risk is not necessarily lower — it is simply not observed between valuation dates.
Illustrative Example
A PE fund reports quarterly NAV changes of +2%, +3%, -1%, +4% over one year. Annualised standard deviation of these four observations is approximately 4%.
A listed equity index tracking similar-size companies might show daily standard deviation of 1%, implying annualised volatility of approximately 16%.
The PE fund appears four times less volatile. But if the same underlying companies were listed and traded daily, they would almost certainly show volatility closer to the listed index. The difference is almost entirely an artefact of valuation frequency, not underlying asset risk.
Volatility vs Drawdown and Liquidity Risk
Volatility is not the same thing as risk. Two strategies with the same standard deviation can have very different risk profiles:
Drawdown risk — A strategy with modest day-to-day volatility can still suffer a severe peak-to-trough loss during a stress event, particularly if it has tail risk (e.g., option-selling strategies). Maximum drawdown is a better indicator of this risk than standard deviation alone. See Sharpe Ratio for discussion of non-normal distributions.
Liquidity risk — A strategy that appears low-volatility because of infrequent valuations may nonetheless be impossible to exit at fair value during a stress event. Low reported volatility in private markets does not mean the investor can redeem at that stated value at any time. See Liquidity Risk.
Concentration risk — A highly concentrated position in one company may show low daily volatility for long periods, then gap sharply on a single event. Volatility as a backward-looking measure does not capture this risk profile.
Common Pitfalls and Misconceptions
Low reported volatility in private markets is partly an artefact of infrequent valuation. It does not indicate that the assets are inherently safer, that returns are more predictable, or that NAV can be accessed at that stated value without discount.
Volatility is backward-looking. Historical volatility may not predict future volatility. A strategy that has operated in a benign environment may experience a regime shift. Structural changes in the underlying market can make historical volatility irrelevant as a forward-looking risk estimate.
Volatility and correlation. A strategy may show low volatility in isolation but become highly correlated with other portfolio assets in stress events. The diversification benefit assumed in normal periods may disappear precisely when it is most needed.
Related Files
Manual Review Notes
- Appraisal smoothing in real estate and infrastructure has been well documented in academic literature (e.g., Geltner 1993 and subsequent work). The concept is described here in general terms consistent with public knowledge; specific empirical estimates should not be cited without a citable source.
- The example annualised volatility of 16% for a listed equity index is illustrative. Actual equity index volatility varies significantly by market, cap size, and time period. Do not cite this as a factual benchmark.