Volatility is how much your portfolio bounces around, expressed as a single annual percentage. A portfolio at 8% volatility has drifted; one at 40% has lurched.
It is the base ingredient for most of the risk grid. Sharpe divides by it, Sortino replaces it with a one-sided version, tracking error applies it to your gap against a benchmark.
How it is calculated
volatility = standard deviation of daily returns × √252
The 252 is the number of trading days in a year. Multiplying by its square root is the standard way of turning a daily figure into an annual one, which is why 8% annual volatility corresponds to daily moves far smaller than 8%.
How to read it
Higher means a wider spread of outcomes, in both directions. Volatility is symmetric: a portfolio that jumps sharply upward is measured as exactly as volatile as one that falls just as sharply.
There is no threshold above which a figure is "too high". What is reasonable depends entirely on what you hold. The comparison that does work is against yourself, over the same length of window, before and after a change in your holdings.
What it misses
- Direction. Two portfolios can post identical volatility while one doubled and the other halved.
- Illiquidity. Concentrated positions and thinly traded assets produce a figure that looks calmer than the position actually is, because the price did not update on the days it would have moved most.
- Period sensitivity. The same portfolio measured over one year and over five produces different numbers.
In practice
In Gylder, volatility sits on the Performance tab of the investments dashboard. Change the date range and every measure in the grid recalculates for that window.
Gylder does not label a figure as high or low, and does not compare yours to a threshold, because any number we picked would be an opinion presented as a fact.
One technical note: deep in history Gylder stores your value series weekly rather than daily to keep the dashboard fast, so volatility across a long window is a slightly smoothed approximation. Honest for reading your portfolio, not a compliance-grade measurement.
Related terms
- Sharpe ratio: return per unit of volatility
- Diversification: how spreading dampens movement
- Portfolio: how composition drives your volatility
Curious how volatile your own portfolio is? Start with a complete, current picture: Tracking your investment portfolio without a spreadsheet.