What is Open Interest in Stock Market?

What is Open Interest in Stock Market?

Open interest is the total number of outstanding contracts held by market traders at the end of the day, including futures and options contracts. It is largely used in the futures market to confirm trends and reversals. As each seller and buyer creates a single contract, open interest tracks the flow of money into the market. To calculate total open interest, just know the totals from one side, buyers or sellers. The open interest position published each day shows the rise or reduction in contracts for that day, expressed as a positive or negative figure.

Understanding Open Interest

The amount of outstanding contracts held by a market trader at the end of a day is referred to as open interest, which can be understood as the number of futures or option contracts that have not yet been exercised, expired, or delivered. It is generally used to confirm trends and track money movement into the market in futures and options contracts. 

Only the totals from either side, buyers or sellers, are required to get the total open interest for a market. The open interest position shows whether the number of contracts rose or decreased daily and is expressed as a positive or negative figure. Understanding open interest in the stock market allows you to gain insight into market activity, investor interest, and prospective liquidity problems.

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Table of Content

  1. Understanding Open Interest
  2. Example of Open Interest
  3. How do Traders Use Open Interest Data in their Trading Strategies?
  4. Benefits of Monitoring Open Interest
  5. Differences Between Open Interest and Trading Volume

Example of Open Interest

The table below shows options market trading activity involving traders A, B, C, D, and E. The amount of open interest is determined by whether traders purchased or sold options to open or cancel positions.




Change in Open Interest

January 1


Buys from B (Open)


January 2


Buys from D (Open)


January 3


Sells to D (Close)


January 4


Buys from C (Open)


January 4


Sells to D (Close)


This series depicts how open interest fluctuates in response to trader activity, such as opening or closing options positions.

  • January 1: Trader A buys one option from Trader B, opening a new position and raising open interest by one.
  • January 2: Trader C purchases five options from Trader D to create additional positions, resulting in a total open interest of six.
  • January 3: Trader A sells one option to D, closing a position and lowering open interest by one.
  • January 4: Trader E purchases five options from C, opening fresh positions. C sells the five options purchased from D at the same time to close positions.

How do Traders Use Open Interest Data in their Trading Strategies?

Open interest is frequently used by traders to evaluate market dynamics in combination with price fluctuations. When prices rise simultaneously with rising open interest, it indicates a positive trend and the formation of new positions. In contrast, dropping prices combined with increased open interest might indicate a negative trend as more contracts are added. Divergences between price and open interest, on the other hand, might give useful information. For example, if prices rise but open interest falls, it might imply that the present trend is losing its strength.

Benefits of Monitoring Open Interest

Here are the benefits of monitoring open interest:

  • A few conclusions can be drawn about the day's activity by watching the change in open interest figures at the end of each trading day.
  • An increase in open interest indicates that new money is flowing into the market. Thus, the current trend will continue (up, down, or sideways).
  • Whenever open interest declines, there may be a liquidation in the market and the current price trend may be coming to an end. It can be useful to know open interest toward the end of major market moves.
  • Often, a levelling off of open interest after a sustained price advance signals the end of an uptrend.

Differences Between Open Interest and Trading Volume

It's easy to confuse open interest with trading volume, but they're two different things. Let's say one trader holds 10 option contracts and sells them to a new trader. Because positions were transferred, not closed or opened, the open interest doesn't change. Whereas, because of the transfer, the trading volume goes up by 10.

Open interest refers to the total number of outstanding contracts held by market participants in the stock market and derivatives markets. Understanding what open interest is can provide you with valuable insights into market participation, liquidity, and potential trend reversals. By monitoring open interest, you can measure the level of investor interest in a particular contract and assess market activity. 
Moreover, changes in open interest can help you confirm trends and identify potential reversals. To navigate the derivatives market efficiently and effectively, you can rely on the BlinkX trading app. The trading app assists you in making well-informed trading decisions based on real-time data, advanced analysis tools, and customisable watchlists.

What Is Open Interest FAQs

At the end of a trading day, open interest refers to the number of outstanding contracts held by market participants. In the futures market, open interest is a measure of the total level of activity.

Yes. Open interest is calculated by adding all positions held by market participants, and then subtracting them once they are closed or settled. Because this is a metric that quantifies the actively held contracts, the numerical value keeps changing every day as new positions are added and closed.

Yes. A contract with a high open interest usually has a higher level of liquidity. Thus, there will be less difference between what one trader wants for an option and what another trader will pay. In this way, it may be easier to buy and sell. Also, a rising open interest indicates that the market is likely to continue its trend around an option.

A rising open interest usually means there is new buying going on, which is a bullish sign. However, having too much open interest can sometimes signal a change in market trends that can be bearish.

A high level of open interest indicates a wide range of options, which indicates liquidity. A low level of open interest indicates a limited number of options available to trade, thereby implying low liquidity.

Open interest indicates the total number of outstanding derivative contracts. It serves as a measure of market activity, showing liquidity and investor interest in a particular financial instrument.

Higher open interest doesn't necessarily indicate a better situation. High open interest signifies more active contracts, but doesn't inherently imply bullish or bearish trends.