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What Is an Envelope?
Let me explain what an envelope is in technical analysis. It's a tool that helps you identify overbought and oversold conditions through upper and lower trend lines based on moving averages.
Envelopes are technical indicators you plot over a price chart, featuring upper and lower bounds. The classic version is the moving average envelope, formed by two moving averages that set those upper and lower price levels.
You use envelopes to spot extreme overbought and oversold conditions, as well as trading ranges.
Key Takeaways
- An envelope refers to trend lines plotted above and below the current price in technical analysis.
- The upper and lower bands are usually based on a simple moving average with a set distance above and below it, though you can use other methods.
- Many traders see a sell signal when price hits or crosses the upper band and a buy signal at the lower band.
How Envelopes Work
You can interpret envelopes in various ways, but most traders use them to define trading ranges. When price hits the upper bound, the security looks overbought, triggering a sell signal. On the flip side, hitting the lower bound means it's oversold, generating a buy signal. This all ties into mean reversion principles.
The bounds are set so price stays within them under normal conditions. For volatile securities, you might use higher percentages to avoid whipsaw signals. Less volatile ones could need lower percentages to produce enough signals.
Combine envelopes with other technical analysis to boost your success rate. For instance, if price breaks out of the envelope, check chart patterns or volume to spot a real turning point. Securities can stay overbought or oversold for a while, after all.
Example of an Envelope
The most common envelope is the moving average type. You create it with a simple or exponential moving average, adding a fixed percentage for upper and lower bounds.
Consider a 5% simple moving average envelope on the S&P 500 SPDR (SPY). Imagine a chart showing the price with upper and lower bands around a 50-day SMA.
The calculations are straightforward: Upper Bound = SMA_50 + SMA_50 * 0.05, Lower Bound = SMA_50 - SMA_50 * 0.05, Midpoint = SMA_50, where SMA_50 is the 50-day Simple Moving Average.
You might short the ETF when price exceeds the upper range and go long when it dips below the lower range. In those scenarios, you'd profit from the mean reversion that follows.
Set stop-loss points at a fixed percentage beyond the bounds, and take-profit at the midpoint line.
