What it is:
How it works (Example):
Although futures and options generally share simultaneous expirations on the third Friday of every month, quadruple witching days only occur four times a year. The last hour of these trading days, from 3:00 to 4:00 p.m. EST, is referred to as the quadruple witching hour.
On quadruple witching days, and especially during quadruple witching hours, many investors attempt to unwind their futures and options positions before the contracts expire. This activity frequently includes repurchasing contracts and closing out position market capitalizations.