Glossary
Open Interest
The total notional value of all open positions in a derivatives market — a measure of how much capital is at risk, separate from volume.
Open interest counts each open contract once. It rises when new positions are opened, falls when existing positions are closed, and is unchanged when one trader's position is transferred to another.
Rising OI alongside a rising price signals new longs entering with real capital; rising OI on a falling price signals new shorts. Open interest is one of the cleanest signals of how much skin traders have in a market — far cleaner than trading volume, which can be double-counted or washed.