Define: TRIN

UK Accounting Glossary

Definition: TRIN


Full Definition of TRIN

The TRIN indicator, also known as the Short Term Trading Index (Short-Term TRading INdex), is a daily market breadth indicator. The TRIN indicator was invented by Richard Arms in 1967 and thus the TRIN is also referred to as the ARMS Index.

It has also been known at various times as MKDS and STKS. The index uses a formula based on NYSE (or Nasdaq) stock market data including a number of advancing and declining issues as well as advancing and declining volume to identify short-term overbought and oversold market conditions.

TRIN Calculation

The index is calculated by dividing the AD Ratio by the AD Volume Ratio as per the following formula:

TRIN = (#Advances / #Declines) / (Advancing Volume / Declining Volume)


  • #Advances is the number of stocks on the NYSE (Nasdaq) increasing in price
  • #Declines is the number of stocks on the NYSE (Nasdaq) decreasing in price
  • Advancing Volume is the total volume of advancing stocks
  • Declining Volume is the total volume of declining stocks


The TRIN has no maximum value and it is difficult to determine peaks except in hindsight. As with any overbought/oversold indicator the TRIN can provide early or false signals.

Application of TRIN

Strong market advances are usually accompanied by relatively low TRIN readings because up volume significantly outweighs down volume to produce a relatively high AD Volume Ratio. This is why the TRIN appears to move with a negative correlation to the market. A strong up day in the market usually results in a lower TRIN.  Conversely, a strong down day tends to result in a higher TRIN.

The TRIN indicator is volatile and is often smoothed using a moving average. Using a 10-period Simple Moving Average (SMA) generally provides relatively clear overbought/oversold signals. The TRIN should be used in conjunction with other indicators or filters.  In particular, a trend indicator should be used to establish market long term trend while the TRIN is used to define entry/exit points.

The TRIN indicator can be displayed with a log scale or an arithmetic scale. Log scaling shows an equal distance for equal percentage movements. Arithmetic scaling shows an equal distance for each unit on the scale.


Synonyms For TRIN

Short Term Trading Index

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Definition Sources

Definitions for TRIN are sourced/syndicated and enhanced from:

  • A Dictionary of Economics (Oxford Quick Reference)
  • Oxford Dictionary Of Accounting
  • Oxford Dictionary Of Business & Management

This glossary post was last updated: 23rd March 2020.