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The total number of outstanding option contracts that haven't been closed.
Why It Matters
Open interest shows how many contracts exist at each strike. High OI means more liquidity and tighter bid-ask spreads. Unusual open interest buildup can signal institutional bets - if someone buys 10,000 calls at a strike, they're betting big on that move.
Key Points
- Updated once daily after market close (unlike volume which is real-time)
- High OI = easier to enter/exit positions at fair prices
- OI increases when new positions open; decreases when positions close
Learn More
Reading an Options Chain
Get a complete explanation with examples, key takeaways, and a quiz to test your knowledge.
Related Terms
Common Questions
The total number of outstanding option contracts that haven't been closed. Open interest shows how many contracts exist at each strike. High OI means more liquidity and tighter bid-ask spreads.
Open interest shows how many contracts exist at each strike. High OI means more liquidity and tighter bid-ask spreads. Unusual open interest buildup can signal institutional bets - if someone buys 10,000 calls at a strike, they're betting big on that move.
Updated once daily after market close (unlike volume which is real-time)
High OI = easier to enter/exit positions at fair prices
OI increases when new positions open; decreases when positions close