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# Elder-Ray Index

## What Is the Elder-Ray Index?

The Elder-Ray Index is a technical indicator developed by Dr. Alexander Elder that measures the amount of buying and selling pressure in a market. This indicator consists of two indicators known as "bull power" and "bear power," which are derived from a 13-period exponential moving average (EMA). These, along with the EMA, help traders determine the trend direction and isolate spots to enter and exit trades.

### Key Takeaways

• The Elder-Ray Index, developed by Dr. Alexander Elder, uses indicators to measure the amount of buying and selling pressure in a market.
• It is designed to be a trend-following system, where the indicators are used to confirm a trade.
• Technical traders should consider long positions if the bull power is rising, bear power is in negative territory and rising (getting weaker), and EMA is sloping upward.
• If the EMA is sloping downward, the bull power is above zero and falling (weakening), and the bear power is falling, traders should consider short positions or selling.

## Understanding the Elder-Ray Index

Technical traders will use the values of bull and bear power, along with divergence, to make trading decisions. Long positions are taken when the bear power has a value below zero but is increasing, and the bull power's latest peak is higher than it was previously (rising). A short position is taken when the bull power value is positive but falling, and the bear power's recent low is lower than it was previously (falling).

The slope of the EMA can also be used in both cases to help confirm the direction of the trend. Traders can watch for the bull and bear signals and then wait for the EMA to start moving in the anticipated direction before taking a trade, or sometimes the EMA will already be moving in a particular direction and then the bull/bear power indicators will provide a confirming trade signal.

Dr. Elder's original methodology generally uses a 13-day exponential moving average (EMA) to gauge the market's consensus of value. This may be altered based on personal preference, and Elder himself utilized 26-day EMAs when analyzing weekly charts. Bull power measures the ability of buyers to drive prices above the consensus value, while bear power measures the ability of sellers to push prices below the consensus value.

Most charting platforms require three windows to be open on one chart when using the Elder-Ray approach.

1. Window one includes a bar or candlestick chart with the 13-period exponential moving average.
2. Window two shows the Elder-Ray Bull Power indicator.
3. Window three shows the Elder-Ray Bear Power indicator.

## Elder-Ray Index Calculation

\begin{aligned} &\text{Bull Power} = \text{Period High} - \text{13 Period EMA} \\ &\text{Bear Power} = \text{Period Low} - \text{13 Period EMA} \\ &\textbf{where:} \\ &\text{Period High and Period Low} = \text{High or low price for the} \\ &\text{time period used, such as a daily chart or a 1-hour chart} \\ &\text{EMA} = \text{Exponential Moving Average} \\ \end{aligned}
1. Calculate the 13-period EMA for the time period being used. If using a daily chart, for example, calculate the EMA based on the last 13 days.
2. Find the period-high price and subtract the 13-period EMA from it to get the bull power value.
3. Find the period-low price and subtract the 13-period EMA from it to get the bear power value.
4. Repeat steps one through three each time a period ends.

## Elder-Ray Index Vs. Average Directional Index (ADX)

The average directional index (ADX) is derived from the Positive Direction Index (+DI) and Negative Direction Index (-DI) which measure bullish and bearish movement similar to the bull and bear power indicators. The main difference is that +DI and -DI are smoothed averages divided by the average true range (ATR). While all these indicators are measuring upward and downward movement, the calculations are quite different and therefore will look different and provide different trade signals on a chart.

## Limitations of Using the Elder-Ray Index

The Elder-Ray Index may be prone to whipsaws, as the bull and bear power indicators will often oscillate above and below zero.

Since the Elder-Ray Index uses a moving average, it is naturally a lagging indicator (although Elder himself called it an oscillating indicator) as it is based on historical price data. Therefore, it may react slowly to price changes. A sell signal, for example, may occur after the price has already dropped significantly—which can be problematic if you are using the indicator for buy and sell signals. To help fix this problem, set stop-loss orders at the time of the trade to help control risk.

Ideally, it's best not to use the Elder-Ray Index in isolation. Rather, combine it with other forms of analysis, such as price action trading, other indicators, or chart patterns.

Article Sources
Investopedia requires writers to use primary sources to support their work. These include white papers, government data, original reporting, and interviews with industry experts. We also reference original research from other reputable publishers where appropriate. You can learn more about the standards we follow in producing accurate, unbiased content in our editorial policy.
1. Dr. Alexander Elder. "Trading for a Living," Page 221. John Wiley & Son, Inc., 1993.

2. Dr. Alexander Elder. "Come Into My Trading Room," Pages 113, 115-117. John Wiley & Son, Inc., 2002.

3. Elder, A. (2014). The new trading for a living: psychology, discipline, trading tools and systems, risk control, trade management. John Wiley & Sons. Pp. 121-123.

4. Dr. Alexander Elder. "Come Into My Trading Room," Pages 130, 135. John Wiley & Son, Inc., 2002.

5. Dr. Alexander Elder. "Trading for a Living," Pages 224-225. John Wiley & Son, Inc., 1993.

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