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| Date | Spot | ATM | Call IV | Put IV | Avg IV |
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Historical Implied Volatility Analysis: How IV Behaved Over Time for US Stocks
Looking at today's implied volatility in isolation is like looking at a single frame of a movie — you see what is happening now but have no context for what came before or what might come next. Historical IV analysis adds the missing dimension by charting how call IV, put IV, and average IV evolved day by day over any lookback period you choose. This time-series perspective reveals the rhythm of volatility for each stock — when it typically spikes, how long those spikes last, what the baseline looks like, and where current IV sits relative to its own history. These patterns are the foundation of volatility trading because they tell you whether current IV is cheap, expensive, or somewhere in the middle.
The chart shows three lines: call IV (green) representing the implied volatility of at-the-money calls, put IV (orange) for at-the-money puts, and average IV (blue) as the mean of both. When call and put IV diverge significantly, it signals an asymmetric market expectation — perhaps a large player is loading up on calls or puts ahead of an event. When both move in tandem, the volatility change is driven by broader market factors. Understanding these dynamics through historical analysis helps you anticipate what IV will do in similar future situations.
Using Historical IV to Find Volatility Trading Edges
The most powerful use of historical IV data is identifying the normal range for each stock and then recognizing when IV has moved outside that range. If a stock's IV has traded between 25 and 45 percent over the past 60 days and currently sits at 48 percent, you know it is historically elevated. This does not mean it will immediately drop, but it does mean option premiums are richer than usual and selling strategies have a statistical edge. Conversely, if IV is at 22 percent — below its recent range — buying strategies have the wind at your back because premiums are historically cheap and likely to mean-revert upward.
The data table below the chart provides the exact daily values for spot price, ATM strike, call IV, put IV, and average IV. This granular data lets you study specific dates when IV made unusual moves, cross-reference those dates with news events or earnings, and build a personal database of cause-and-effect relationships that sharpen your future volatility trading.
Frequently Asked Questions About Historical IV
What lookback period should I use for IV analysis?
A 30-day lookback captures recent volatility behavior and is useful for short-term trading decisions. A 60 to 90-day lookback provides more context and smooths out single-day anomalies. The right period depends on your trading timeframe. Short-term traders should use 20 to 30 days, swing traders should use 45 to 60 days, and position traders benefit from 90 to 120 days of history.
Why do call IV and put IV sometimes diverge?
Divergence between call and put IV happens when there is asymmetric demand for one side of the market. Heavy call buying pushes call IV up while put IV stays stable, and vice versa. This often occurs ahead of expected directional events. When the divergence is extreme, it represents a strong consensus about direction — which sometimes creates contrarian opportunities if the consensus is wrong.
Disclaimer: Options trading involves substantial risk. Historical IV analysis is for educational and informational purposes only and should not be construed as financial advice. Past volatility patterns do not guarantee future behavior.