How volatility works
Volatility measures how much a price moves over a period, usually as an annualised standard deviation of returns. Historical volatility looks backward at what already happened; implied volatility is the market’s forward-looking estimate priced into options. High volatility means wider swings in both directions, which raises both the opportunity and the risk on every position. It is a measure of movement, not of direction.
Worked example
An asset with 80 percent annualised volatility, common in crypto, can routinely swing 5 percent in a day; a major forex pair near 8 percent volatility rarely moves 1 percent. The same dollar position carries far more risk on the volatile asset, so position size must shrink as volatility rises to keep risk constant. This is why a fixed lot size is dangerous across instruments: it holds size constant while risk varies.
Trading volatility itself
Beyond direction, traders take views on volatility: expecting calm, expecting a spike, or harvesting the gap between implied and realised. These are advanced expressions, usually through options or carefully sized positions. The starting discipline is simpler: size every trade to the instrument’s current volatility, not to a habit, and widen stops on volatile assets so normal noise does not stop you out.
Why it matters
Volatility, not headline price, is what determines correct position size and stop distance. A strategy tuned to a calm regime can be destroyed by a volatile one using identical rules. Read the market’s volatility before sizing, and reduce exposure when it expands. Related: drawdown and position sizing.
Learn more in our learn trading hub.
