Open Interest is the total number of outstanding contracts that are held by
market participants at the end of the day.
It can also be defined as the total number of futures contracts or option
contracts that have not yet been exercised (squared off), expired, or fulfilled
by delivery.
Open interest applies primarily to the futures market. Open interest, or the
total number of open contracts on a security, is often used to confirm trends
and trend reversals for futures and options contracts.
Open interest measures the flow of money into the futures market. For each
seller of a futures contract there must be a buyer of that contract. Thus a
seller and a buyer combine to create only one contract.
Therefore, to determine the total open interest for any given market we need
only to know the totals from one side or the other, buyers or sellers, not the
sum of both.
The open interest position that is reported each day represents the increase or
decrease in the number of contracts for that day, and it is shown as a positive
or negative number.
How to calculate Open Interest
Each trade completed on the exchange has an impact upon the level of open
interest for that day.
For example, if both parties to the trade are initiating a new position ( one
new buyer and one new seller), open interest will increase by one contract.
If both traders are closing an existing or old position ( one old buyer and one
old seller) open interest will decline by one contract.
The third and final possibility is one old trader passing off his position to a
new trader ( one old buyer sells to one new buyer). In this case the open
interest will not change.
Benefits of monitoring open interest
By monitoring the changes in the open interest figures at the end of each
trading day, some conclusions about the day’s activity can be drawn.
Increasing open interest means that new money is flowing into the marketplace.
The result will be that the present trend ( up, down or sideways) will continue.
Declining open interest means that the market is liquidating and implies that
the prevailing price trend is coming to an end. A knowledge of open interest can
prove useful toward the end of major market moves.
A leveling off of open interest following a sustained price advance is often an
early warning of the end to an uptrending or bull market.
Open Interest - A confirming indicator
An increase in open interest along with an increase in price is said to confirm
an upward trend. Similarly, an increase in open interest along with a decrease
in price confirms a downward trend. An increase or decrease in prices while open
interest remains flat or declining may indicate a possible trend reversal.
The relationship between the prevailing price trend and open interest can be
summarized by the following table.
Price Open Interest Interpretation
Rising Rising Market is Strong
Rising Falling Market is Weakening
Falling Rising Market is Weak
Falling Falling Market is Strengthening
