Open interest
The number of option contracts currently outstanding at a given strike and expiration — positions opened and not yet closed, exercised, or expired. Unlike volume, it carries over from day to day.
Open interest tells you where positions already live; volume tells you where trading happened today. High open interest usually accompanies tighter markets because closing flow provides natural liquidity.
One caution: open interest counts contracts, not opinions. A large number says nothing by itself about whether the crowd is long or short them.
Related terms
← All terms · Ready to see it in context? Start with thefree curriculum.