Open interest

Open interest (also known as open contracts or open commitments) denotes the total number of derivative contracts, such as futures and options, that are currently active on:a specific underlying security, andthat have identical terms. That is, the total contracts for a specific strike price and expiration date, that have been traded, but have not yet expired, have not yet been closed through a closing transaction, or have not yet been terminated via early exercise. A closing transaction occurs when a counterparty that is long the contract sells, or, conversely, when a counterparty that is short the contract buys.
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The total number of derivative contracts traded that have not yet been liquidated either by an offsetting derivative transaction or by delivery. Related: liquidation

For futures, the total number of contracts not yet liquidated by offset or delivery; i.e., the number of contracts outstanding. Open interest is determined by counting the number of transactions on the market (either the total contracts bought or sold, but not both). For futures options, the number of calls or puts outstanding; each type of option has its own open interest figure.