On the third Friday of March, June, September, and December, multiple derivative contracts expire simultaneously. That quarterly collision is “witching” — and the difference between “triple” and “quad” is just which contracts are counted.
Triple vs quad
Triple witching refers to three expirations landing together: stock-index futures, stock-index options, and single-stock options. Quad witching adds a fourth — single-stock futures. The terms have been used loosely and interchangeably over the years as products came and went, so you'll hear both for the same quarterly day. What matters isn't the count in the name; it's that a lot of derivatives expire at once.
Why the day is heavy
Because it's quarterly, witching Fridays clear the largest accumulated open interest of the cycle — index hedges, structured positions, and months of built-up contracts. Volume spikes, especially at the open and into the close, as positions settle and roll. Pinning to major strikes and max pain can be strong into it, and a big chunk of gamma expires at once.
Witching isn't a direction — it's volume and expiring gamma. Trade the structure, not a thesis about which way the “witch” points.
How to trade it
Expect elevated volume and pinning into the day, and respect that much of the intraday move can be mechanical settlement flow rather than directional conviction. The bigger opportunity is often after: with quarterly gamma gone, the following days tend to unclench and move more freely. Read witching as a scheduled, flow-heavy event — and read the fresh map that prints once it clears.