How are Total Industry Volume and Open Interest fields calculated?

Both fields are provided in the EOD Trade Outline products and sourced from the Options Clearing Corp (OCC), calculated across all U.S. options exchanges. Total Industry Volume is based on the day’s volume for the reported trading date, for each security. For ISE/GEMX, Total Industry Volume is calculated by the number of contracts per side. This will result in the field displaying exactly double that of PHOTO/NOTO/MRX/BX. The same is not true for Total Exchange Volume where the calculation is done by counting the number of contracts total as opposed to contracts per side.

Open Interest is a snapshot for each security from the end of day of the reported trading date. Open Interests shows the total number of outstanding contracts for each series across all options exchanges. Increases in open interest indicate a net increase in opening long positions. There is potential for more activity in series with larger Open Interest since there is the potential for closing trades to reduce the number of outstanding contracts.