Online Trading Concepts

Open Interest

Open Interest

  1. Open Interest Basics
  2. Interpreting Open Interest

Open Interest (OI) is the number of contracts outstanding in the marketplace. Open Interest only applies to futures and option contracts. Changes in open interest may confirm price action or act as a warning of a potentially weakening trend.

A hypothetical situation is given next to help grasp the concept of Open Interest:

open interest changes as future contract months expire

Generally open interest increases over the life of the futures contract (note: futures contracts expire, same with options). When futures contract months or quarters transition from one month or quarter to the next month or quarter, the future closest to expiration (called the "front month") decreases in open interest and the next futures contract (called the "back month") increases. This is shown with the chart of the E-mini S&P 500 Futures contract above.

The chart above of the E-mini S&P 500 Futures contract shows both the March S&P 500 future and the June S&P 500 future as the futures near March expiration. Note how the March and June futures contract open interest rises steadily over time; this is normal over the life of a futures contract.

Also note the dramatic decrease in the open interest of the March S&P future as the contract is nearing expiration. In contrast, note the dramatic increase of the June S&P futures contract as futures traders "roll over" their futures positions to the next futures expiration contract (June).

Interpreting Open Interest is up next.

Next Page - Interpreting Open Interest

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