Implication of Open Interest in Futures Markets

What is Open Interest ?

The bookish definition says that Open Interest is the total number of outstanding contracts that are held by market participants at the end of the day. In other words, Open Interest is the total number of future contracts or option contracts that have not yet been exercised, expired or filled. Open Interest makes sense only for Futures market.

Open Interest measures the flow of money into the futures market and hence is used by traders to confirm trends and trend reversals in futures market. The open interest position that is reported each day represents the increase or decrease in the number of contracts for that day and hence is shown as a positive or negative number.

Open Interest Calculation :

A contract has both a buyer and a seller. The open interest for a day is the increase or decrease in the number of contracts for that day. For example, if 2 parties in a trade are initiating a new position i.e. 1 new buyer and 1 new seller are entering into the market, open interest would increase by one contract. On the other hand, if 2 parties in a trade are closing an existing position, open interest would decrease by one contract. There is one more possibility wherein one old trader passes its position to a new trader. In this case, open interest does not change.

Benefits of monitoring Open Interest :

In short, increasing open interest means that money is flowing into the market. Due to this, the present trend will continue. If the current trend is upward, it would remain upward. If it is downward, it would remain downward. Declining Open Interest means that current market trend is coming to an end. If the price jumps significantly but open interest remains leveled, it is an early warning to the end of bull market and vice-versa. Hence, an increase or decrease in prices while open interest remains same is an early indication of trend reversal.

Further reading:
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