Noun
triple witching (uncountable)
(finance) Simultaneous expiry on US markets of stock index futures, stock index options, and stock options, which took place on the third Friday of March, June, September, and December. (With the introduction of single stock futures those days are now quadruple witching.)
"To the Illuminati, this is a year for which they've long awaited -- the triple witching of the Beast year." (November 1997). Texe Marrs