Open interest (OI) is the number of open futures and options contracts. Comparing today's change in OI with today's price change shows whether new positions are being opened or old ones closed.
| Price | OI | Name | Usual reading |
|---|---|---|---|
| Up | Up | Long build-up | New buyers entering: bullish |
| Down | Up | Short build-up | New sellers entering: bearish |
| Up | Down | Short covering | Sellers closing their positions: a rise that may not last |
| Down | Down | Long unwinding | Buyers closing their positions: a fall that may not last |
The biggest OI changes matter most. A stock with a 15% jump in OI and a 3% price rise shows much stronger long build-up than one with a 1% OI change.