The Arms Index, also known as TRIN, an acronym for TRading INdex, was developed in 1967 by Richard Arms. It is a volume-based indicator, which determines market strength and breadth by analyzing the relationship between advancing and declining issues and their respective volume; it is used to measure intra-day market supply and demand, and it can be applied over short or longer time periods.
To calculate the Arms Index you need the following data:
1) advancing issues
2) declining issues
3) advancing volume
4) declining volume
As far as I know none of the data service providers in India provide this data. (Please correct me if I am wrong and provide me the source of this data provider).
The Arms Index is calculated using the following formula:
(# of advancing issues / # of declining issues)
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(advancing volume/declining volume)
Interpretation
The Arms Index is primarily a short-term trading tool. The Index shows whether volume is flowing into advancing or declining stocks. If more volume is associated with advancing stocks than declining stocks, the Arms Index will be less than 1.0; if more volume is associated with declining stocks, the Index will be greater than 1.0.
The Index is usually smoothed with a moving average. I suggest using a 4-day moving average for short-term analysis, a 21-day moving average for intermediate-term, and a 55-day moving average for longer-term analysis.
Normally, the Arms Index is considered bullish when it is below 1.0 and bearish when it is above 1.0. However, the Index seems to work most effectively as an overbought/oversold indicator. When the indicator drops to extremely overbought levels, it is foretelling a selling opportunity. When it rises to extremely oversold levels, a buying opportunity is approaching.