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Arms Index (TRIN)

Arms Index (TRIN)

What Is the Arms Index (TRIN)?

The Arms Index, likewise called the Short-Term Trading Index (TRIN) is a technical analysis indicator that compares the number of progressing and declining stocks (AD Ratio) to progressing and declining volume (AD volume). It is utilized to check overall market sentiment. Richard W. Arms, Jr. designed it in 1967, and it measures the relationship between market supply and demand. It fills in as a predictor of future price developments in the market, principally on a intraday basis. It does this by generating overbought and oversold levels, which show when the index (and the majority of stocks in it) will change heading.

The Formula for Arms Index (TRIN) is:

TRIN = Advancing Stocks/Declining StocksAdvancing Volume/Declining Volumewhere:Advancing Stocks = Number of stocks that are higheron the dayDeclining Stocks = Number of stocks that are loweron the dayAdvancing Volume = Total volume of all advancingstocksDeclining Volume = Total volume of all decliningstocks\begin &\text\ =\ \frac{\text{Advancing Stocks/Declining Stocks}}{\text{Advancing Volume/Declining Volume}}\ &\textbf\ & \begin \text\ =\ &\text\ &\text\end\ &\begin \text\ =\ &\text\ &\text\end\ &\begin \text\ =\ &\text\ &\text\end\ &\begin\text\ =\ &\text\ &\text\end \end

Step by step instructions to Calculate the Arms Index (TRIN)

TRIN is given in many charting applications. To work out the hard way, utilize the accompanying advances.

  1. At set intervals, like clockwork or daily (or anything interval is picked), track down the AD Ratio by separating the number of propelling stocks by the number of declining stocks.
  2. Partition total propelling volume by total declining volume to get AD Volume.
  3. Partition the AD Ratio by AD Volume.
  4. Record the outcome and plot on a graph.
  5. Repeat the calculation at the next picked time interval.
  6. Interface various data points to form a graph and perceive how the TRIN moves over the long haul.

What Does the Arms Index (TRIN) Tell You?

The Arms index tries to give a more dynamic clarification of overall developments in the composite value of stock exchanges, like the NYSE or NASDAQ, by breaking down the strength and breadth of these developments.

An index value of 1.0 shows that the ratio of AD Volume is equivalent to the AD Ratio. The market is supposed to be in a neutral state when the index equals 1.0, since the up volume is uniformly distributed over the propelling issues and the down volume is equitably distributed over the declining issues.

Numerous analysts accept that the Arms Index gives a bullish signal when it's under 1.0, since there's greater volume in the average up stock than the average down stock. As a matter of fact, a few analysts have found that the long-term equilibrium for the index is below 1.0, possibly affirming that there is a bullish bias to the stock market.

Then again, a perusing of greater than 1.0 is normally viewed as a bearish signal, since there's greater volume in the average down stock than the average up stock.

The farther away from 1.00 the Arms Index value is, the greater the differentiation among buying and selling on that day. A value that surpasses 3.00 shows an oversold market and that bearish sentiment is too emotional. This could mean a vertical reversal in prices/index is coming.

On the other hand, a TRIN value that dips below 0.50 may demonstrate an overbought market and that bullish sentiment is overheating.

Traders look at the value of the indicator as well as at how it changes over the course of the day. They search for extremes in the index value for signs that the market may before long change headings.

The Difference Between the Arms Index (TRIN) and the Tick Index (TICK)

TRIN compares the number of progressing and declining stocks to the volume in both progressing and declining stocks. The Tick index compares the number of stocks making a uptick to the number of stocks making a downtick. The Tick Index is utilized to check intraday sentiment. The Tick Index doesn't factor volume, yet extreme readings actually signal possibly overbought or oversold conditions.

Limitations of Using the Arms Index (TRIN)

The Arms Index has a couple of mathematical eccentricities that traders and investors ought to know about while utilizing it. Since the index accentuates volume, mistakes emerge when there isn't as much propelling volume in that frame of mind true to form. This may not be a regular situation, but rather a situation can emerge and might actually make the indicator untrustworthy.

The following are two instances of examples where problems might happen:

  • Assume that an extremely bullish day happens where there are two times however many propelling issues as declining issues and two times as much propelling volume as declining volume. In spite of the extremely bullish trading, the Arms Index would yield just a neutral value of (2/1)/(2/1) = 1.0, recommending that the index's perusing may not be completely accurate.
  • Assume that another bullish scenario happens where there are three times however many propelling issues as declining issues and two times as much propelling volume than declining volume. In this case, the Arms Index would really yield a bearish (3/1)/(2/1) = 1.5 perusing, again proposing an error.

One method for tackling this problem is separate the two parts of the indicator into issues and volume as opposed to involving them in a similar equation. For example, propelling issues partitioned by declining issues could show one trend, while propelling volume over declining volume could show a separate trend. These ratios are called the advance/decline ratio and upside/downside ratio, separately. Both of these might measure up to recount the market's true story.


  • The Arms Index moves inverse the price direction of the Index. As examined over, a strong price rally will see TRIN move to bring down levels. A falling index will see TRIN push higher.
  • On the off chance that AD Volume has a lower ratio than AD Ratio, TRIN will be over one.
  • A TRIN perusing over one regularly goes with a strong price decline, since the strong volume in the decliners helps fuel the selloff.
  • On the off chance that AD Volume makes a higher ratio than the AD Ratio, TRIN will be below one.
  • A TRIN perusing below one normally goes with a strong price advance, since the strong volume in the rising stocks helps fuel the rally.