The current allocation of volume, open interest, and a lot more cotton futures information, can be found on the ICE futures website under “Featured Reports”. Volume (viewed above as the green line) is defined as the total daily number of contracts traded in a session. The level of volume is often used to gauge the strength of continuing or changing trends. Typical cotton daily volume bounces around between 10,000 and 25,000 contracts. The week ending Thursday, July 2 had lower than average volumes ranging from only 8,837 contracts (on Friday June 26) to 35,897 contracts (on July 1). The Jul’20 and Dec’20 contracts had most of the volume, as of July 1.
Open interest (the red line above) refers to the number of active positions at the end of the day (not double counting both the buyer and seller). Open interest by contract has a similar front month concentration as does volume. Open interest does not fluctuate as much as daily volume, but there are patterns where sharp surges or declines in open interest are associated with sudden rallies or sell-offs (often accompanied by spikes in volume). Index fund rebalancing for the new month/quarter probably played a role in higher open interest on July 1 and 2, in addition to explaining higher volumes and price.