Historic volatility is the standard deviation of the "price returns" over a given number of sessions, multiplied by a factor (260 days) to produce an annualized volatility level. A "price return" is the natural logarithm of the percentage price changes or ln[Pt/P(t-1)].

A volatile market therefore has a larger standard deviation and thus a higher historical volatility value. Conversely, a market with small fluctuations has a small standard deviation and a low historical volatility value. Historical volatility are available in the daily chart and statistics section of our site.

Historical volatility can also be used as a tool by traders who are trading only the underlying instrument. Quantifying the volatility in a market can affect a trader's perception of how far the market can move and thus provides some help in making price projections and placing orders. High volatility may indicate a trend reversal as heavy buying/selling comes into the market and may sharp price reversals.