Therefore, if there are 50 opening transactions and 25 closing transactions at XYZ's September 45 call on Wednesday, daily volume at that strike is 75 contracts. Meanwhile, open interest refers to ...
"Data As Of" refers to the Closing Sale. Volume is updated throughout the after hours market. Note: Daily closing values are valid as of 5:15 p.m. ET. Duplicate values disseminated after 5:15 p.m. ET.