What Is Open Interest and How Traders Use It

Short answer: Open interest is the total number of outstanding futures or options contracts that have not been closed or settled, and traders use it alongside price and volume to gauge the strength of a trend.

What Open Interest Measures

Open interest counts how many contracts are currently open in the market. It rises when new positions are created and falls when positions are closed. Unlike volume, which counts all trades in a session, open interest reflects the net positions still live.

Open Interest vs Volume

Volume tells you how active trading was during a period, while open interest tells you how many positions remain open. A contract can have high volume but flat open interest if traders are mostly closing and opening positions against each other.

Reading Price With Open Interest

Traders combine the two. Rising price with rising open interest suggests new money supporting an uptrend (bullish). Rising price with falling open interest may suggest short covering rather than fresh buying. Falling price with rising open interest can signal new short positions (bearish). These are guides, not certainties.

Use in Options

In options, high open interest at particular strike prices can indicate where many traders expect the market to settle or where strong support and resistance may form. Some traders watch these levels for clues to likely price magnets near expiry.

Liquidity Indicator

High open interest generally means a contract is liquid, with tighter spreads and easier entry and exit. Low open interest contracts can be hard to trade without moving the price.

Limitations

Open interest is a confirming indicator, not a predictor. It should be used with price action, volume, and broader analysis, not in isolation. Interpretations can be ambiguous, so treat it as one input among several in your trading decisions.

This explainer was written by The Dispatch desk to answer a question readers commonly ask. It is general information, not personalised financial advice.