Triple Witching

The quarterly expiration of stock options, index options, and index futures on the same day.

Triple witching happens on the third Friday of March, June, September, and December, when stock options, stock index options, and stock index futures all expire simultaneously. The overlapping expirations can cause a surge in trading volume and volatility as traders roll over or close positions before the closing bell.

Trading desks braced for extra volatility heading into triple witching, when billions of dollars in contracts expire at once.