Historical Volatility
Risk ManagementA statistical measure of how much a currency pair's price has fluctuated over a specific past period. Calculated as the standard deviation of returns, it is expressed as an annualized percentage.
What Is Historical Volatility?
Historical volatility (HV) looks backward at actual price data to quantify how much a pair has moved. It is calculated by finding the standard deviation of daily (or other periodic) price returns, then annualizing the result. An HV of 10% on EUR/USD means that, based on recent history, the pair's annualized price fluctuation has been about 10% of its current value.
HV is typically measured over 10, 20, 30, or 90 days. Shorter windows respond faster to recent changes but are noisier. Longer windows are smoother but slower to reflect current conditions.
Historical vs. Implied Volatility
Historical Volatility tells you what has already happened. Implied Volatility tells you what the market expects to happen. When implied volatility is significantly higher than historical volatility, the market is pricing in a potential large move (often around a scheduled event like a central bank meeting). When implied is lower than historical, the market expects calmer conditions ahead.
Using Historical Volatility
Compare a pair's current HV to its own average over the past year. If current HV is well below average, a volatility expansion may be coming, which is useful for breakout strategies. If current HV is elevated, mean-reversion and range strategies may struggle. HV also helps with Position Sizing: pairs with higher historical volatility should receive smaller position sizes to keep risk per trade constant.
Related Terms
Volatility
The degree to which a currency pair's price fluctuates over a given period. High volatility means large price swings; low volatility means the price moves in a narrow range.
Implied Volatility
The market's forecast of future price movement for a currency pair, derived from the prices of forex options. Higher implied volatility signals that traders expect larger price swings ahead.
Average True Range
A volatility indicator that measures the average range of price bars over a specified period, accounting for gaps. ATR does not indicate direction but shows how much a pair typically moves, helping traders set appropriate stop-losses and position sizes.
Bollinger Bands
A volatility indicator consisting of three lines: a middle simple moving average (typically 20-period) and upper and lower bands set at 2 standard deviations above and below it. The bands expand during high volatility and contract during low volatility.