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Trin Indicator Arms Index Analysis

Did you know about the TRIN index? It’s a stock market indicator that’s been around since 1967, yet it’s often overlooked. Whether you’re a contrarian trader looking to identify extremes or someone who wants to time major market tops and bottoms, TRIN can be incredibly useful. By combining this indicator with price action analysis, you can vastly improve your timing and conviction on both the long and short side.

Read on to learn more about how the TRIN indicator is calculated, how to interpret it, how to use it as a contrarian signal, how to combine it with other indicators, and best practices for implementation.

Understanding the trin stock market indicator

The stock market is filled with technical indicators that traders use to analyse market conditions and identify trading opportunities. One such powerful yet often overlooked indicator is the TRIN index, also known as the Arms Index or the Short-Term Trading Index. 

What is the trin indicator?

The TRIN indicator was developed in 1967 by Richard W. Arms Jr. It is calculated by taking the ratio between advancing/declining stock numbers and the ratio of advancing/declining volumes. The official formula is:

TRIN = (Advancing Stocks/Declining Stocks) / (Advancing Volume/Declining Volume)

By comparing breadth and depth, the TRIN index provides insight into overall market sentiment. It shows whether volume is flowing into advancing or declining stocks, allowing traders to gauge relative supply and demand.

The indicator typically ranges from 0 to 3, with a reading below 1 indicating bullish sentiment and above 1 indicating bearish sentiment. A reading near 1 suggests an evenly balanced market.

How is the trin indicator calculated?

Manually calculating the TRIN index requires gathering four key market data points:

1. Advancing Stocks: The number of stocks that closed up for the day

2. Declining Stocks: The number of stocks that closed down for the day  

3. Advancing Volume: The total volume traded in advancing stocks  

4. Declining Volume: The total volume traded in declining stocks

With this data, you can plug into the TRIN formula:

TRIN = (Advancing Stocks/Declining Stocks) / (Advancing Volume/Declining Volume)

For example, if there were 1700 advancing stocks and 1300 declining stocks, alongside a total advancing volume of 80 million and a declining volume of 100 million, the calculation would be:

TRIN = (1700/1300) / (80,000,000/100,000,000) = 1.31

A reading of 1.31 indicates a bearish sentiment in this market. Most traders will use a charting platform rather than calculate TRIN manually.

How to use trin indicator?

When using the TRIN in your analysis, focus on the absolute level as well as the directional slope:

  • Below 1.0 = Bullish Sentiment 
  • Between 1.0-1.5 = Evenly Balanced
  • Above 1.5 = Bearish Sentiment

A rising TRIN indicates bearish momentum is accelerating, while a falling TRIN shows bullish momentum is accelerating.

There are also extremes to watch for in TRIN readings:

  • Below 0.50 = Overbought Market
  • Above 3.00 = Oversold Market 

These extremes suggest sentiment may have become overly bearish or bullish, increasing the odds of a reversal.

Trin as a contrarian indicator

One of the main uses for the TRIN index is as a contrarian indicator. Since most traders tend to overreact to news events and price swings, the TRIN allows you to measure when market sentiment may have become too extreme.

Rather than follow the herd, contrarian traders will look to take the opposite side of the market when TRIN breaches key thresholds. For example, if TRIN drops below 0.50, signalling an overbought reading, a contrarian trader may start shorting overextended stocks or sectors.

Combining TRIN with price action analysis and other sentiment indicators can further confirm whether investor sentiment aligns with extreme overbought or oversold readings.

Using trin for market tops and bottoms

In addition to identifying intraday trades, the Arms Index also has usefulness around major market turning points. TRIN often spikes above 3.0 near intermediate and long-term bottoms as selling climaxes. Conversely, readings below 0.50 are common around intermediate and long-term market tops when buying euphoria peaks.

By combining other technical indicators with Arms Index analysis, traders can measure exhaustion trends and improve timing on bigger-picture trades. Some examples include combining with moving average crossovers, momentum fluctuation like trin indicator for nifty, MACD and RSI, or chart pattern breakouts.

Arms index vs. other sentiment indicators 

The TRIN indicator shares similarities with other market sentiment gauges like the put/call ratio and volatility indexes (VIX). However, the Arms Index analysis includes volume flows rather than just price action. This allows for assessing both the breadth and depth of market moves.

Some benefits of using TRIN over other sentiment indicators include:

  1. Captures intraday market internals rather than just closing date
  2. Doesn’t rely on subjective survey data
  3. Accounts for volume with breadth metrics 
  4. Has usefulness for contrarian trading strategies

For these reasons, many short-term traders will use TRIN in conjunction with other sentiment indicators to confirm overbought or oversold readings.

Limitations of the trin index

While Arms Index TRIN analysis can certainly improve trading decisions, there are some drawbacks to consider:

  1. Intraday readings can whipsaw frequently
  2. Spikes above 3.0 or below 0.50 don’t always perfectly time tops/bottoms
  3. Requires an understanding of contrarian interpretation
  4. Works best when confirmed with other indicators
  5. Lacks customisation beyond raw formula

Traders should use TRIN in combination with price action and other market indicators rather than relying solely on absolute levels. Conservative traders may also consider waiting for a TRIN signal to be confirmed by a reversal candlestick pattern or momentum shift.

Trin index best practices

Here are some tips for effectively applying the Arms Index formula within your trading plan:

  1. Use daily charts to smooth day-to-day volatility 
  2. Identify potential trade signals when TRIN diverges from price action
  3. Look for oversold above 3.0 and overbought below 0.50
  4. Combine TRIN signals with other indicators for confirmation 
  5. Wait for confirmation of candlestick patterns before entering
  6. Consider contrarian interpretation of extreme readings  
  7. Use TRIN to calculate exhaustion at market tops and bottoms

By following these best practices, TRIN can provide high-probability trade signals, especially when sentiment becomes stretched by irrational exuberance or pessimism. Just maintain reasonable expectations when using it as part of an overall trading approach.


TRIN is a market sentiment tool that uses breadth and volume metrics. It identifies oversold readings above 3.0 and overbought levels below 0.50, which traders can profit from. When combined with price action confirmation, TRIN signals create a robust trading approach, useful for both short-term and long-term investors. TRIN can help investors find opportunities by identifying unpopular or undervalued stocks.


What does a TRIN reading below 1 and above 1 indicate?

A TRIN reading below 1 generally indicates bullish sentiment in the market, whereas a TRIN reading above 1 generally indicates bearish sentiment in the market.

What are extreme TRIN readings that traders should watch for?

Traders watch for TRIN readings below 0.50 to signal an overbought market and TRIN readings above 3 to signal an oversold market.

How can TRIN be used as a contrarian indicator?  

TRIN can identify when market sentiment may have become too extreme, allowing contrarian traders to take the opposite side.

How does TRIN incorporate volume analysis?

Unlike other sentiment indicators, TRIN analysis looks at both the breadth of advancing/declining stocks and the volume flowing into them.

What are some best practices for using TRIN effectively?  

Best practices include:
Smoothing volatility with daily charts.
Waiting for confirmation signals.
Using contrarian interpretations of extreme overbought/oversold readings.

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