Volatility & VIX

Most people think risk means "the chance of losing money." Professionally, risk means something more precise: uncertainty about outcomes. Volatility is how that uncertainty is measured — the statistical spread of returns around their average. A stock that moves 1% per day is less volatile than one that moves 5% per day, regardless of direction. Understanding volatility is understanding the language of risk.

Standard deviation — the core measure

Standard deviation measures how widely returns are dispersed around their average. A stock with an annualised standard deviation of 15% will spend about two-thirds of all years within 15% of its average return. About 95% of years will fall within 30% (two standard deviations). About 99.7% within 45% (three standard deviations).

Historical vs implied volatility

Historical volatility (HV) looks backward — it measures how much an asset has moved over a past period (typically 30 or 90 days). Implied volatility (IV) looks forward — it's extracted from options prices and represents what the market expects future volatility to be. When IV is much higher than HV, the market is pricing in more uncertainty than recent history suggests — usually because a known risk event (earnings, central bank meeting, referendum) is approaching.

The VIX — the market's fear gauge

The VIX (CBOE Volatility Index) measures the 30-day implied volatility of S&P 500 options. It's the market's collective forecast of how much the S&P 500 will swing over the next month. A VIX of 15 means the market expects roughly ±4.3% monthly moves. A VIX of 40 means ±11.5%.

Volatility as opportunity

High volatility is uncomfortable but creates opportunity. When the VIX spikes above 40, it often signals capitulation — the most fearful moment, which historically precedes recovery. When VIX is below 12 (extreme calm, overconfidence), it often precedes periods of elevated risk. The long-term investor's edge: being able to hold through high volatility periods, or better, add during them.