Price swings, measured
Every day, stock prices move. Some days the change is 0.1%. Some days it is 5%. Volatility is a statistical measure of how large and frequent those swings are. The standard calculation is the standard deviation of daily returns, then scaled to an annualised figure. A stock with 20% annualised volatility is expected (with roughly 68% confidence) to trade within a range of ±20% around its expected return in a given year.
Typical volatility by asset class
| Asset | Typical annual volatility |
|---|---|
| Short-term government bonds | 2–4% |
| Long-term government bonds | 8–12% |
| Large-cap equities (S&P 500) | 15–20% |
| Small-cap equities | 25–35% |
| Emerging market equities | 25–40% |
| Bitcoin | 60–80% |
Volatility vs permanent loss
A stock that swings 30% in a year is not necessarily a bad investment — if it ends the year up 40%, you did well despite the turbulence. Volatility captures the journey, not the destination. Long-term investors who tolerate a bumpy ride are often compensated for doing so: equities, despite far higher volatility than bonds, have historically delivered superior returns over decades.
The VIX: implied future volatility
The CBOE Volatility Index (VIX) measures expected volatility in the S&P 500 over the next 30 days, derived from options prices. When investors are fearful, they pay more for protective put options, which pushes the VIX higher. Below 15 signals calm; above 30 signals stress; above 40 suggests outright panic.
"Volatility is the price of admission for superior long-run returns. The investor who refuses to pay it is guaranteed to earn less."
What this means for you
Before investing in anything, ask: how much volatility can I psychologically tolerate without panic-selling at the bottom? A portfolio that lets you sleep at night — even if it's theoretically suboptimal — will beat a perfect portfolio you abandon at the worst moment. Match your asset allocation to your actual risk tolerance, not just your theoretical time horizon.