Options Expiry and Quadruple Witching

Four times a year, four classes of derivatives expire on the same Friday. Volume surges, gamma exposure drives price toward strikes, and the market behaves oddly. That day is quadruple witching — and traders who don't know the calendar get run over by it.

Options expiration is a recurring structural event that distorts the underlying market for days before and after.

The expiration calendar

US options expire on a regular schedule:

• Monthly: the third Friday of each month
• Weekly: most Fridays on major indices
• Quarterly (expires): last trading day of the quarter
• LEAPS: January of the year specified

Most retail flow clusters around monthly expiration.

Quadruple witching

Four times a year — the third Friday of March, June, September, December — four derivative classes expire simultaneously:

Class	Example
Stock index futures	E-mini S&P futures
Stock index options	SPX options
Stock options	Single-name equity options
Single-stock futures	(lower volume, but listed)

This is quadruple witching. (Before single-stock futures existed, it was triple witching.) It produces the highest volume days of the quarter and notable gamma-driven movement.

The gamma effect

Market makers (dealers) who sell options must hedge by holding the underlying. As expiry approaches, gamma — the rate of change of delta — peaks. Dealer hedging creates a "pin" effect:

• Positive dealer gamma: dealers hedge against the move, dampening volatility — price gets pinned near large open-interest strikes
• Negative dealer gamma: dealers hedge with the move, amplifying volatility — trends accelerate

Near expiry, the largest open-interest strikes act like magnets. Price often drifts toward them as dealers hedge into the close.

Pin risk

On expiry day, options near the money face pin risk: an option that finishes in the money by a penny is exercised; one cent out expires worthless. Sellers of those options have a strong incentive to push (or defend) the strike — creating sharp, localized moves around large strikes.

Max pain

"Max pain" theory holds that price gravitates toward the strike at which the most options expire worthless. The effect is modest and contested, but the open-interest structure around large strikes is real.

Practical effects on the underlying

• Volume spike on expiry Fridays, especially witching
• Reduced volatility after expiry as gamma rolls off
• Strike magnetism into the close
• Dealer rebalancing the following Monday
• Index rebalances (S&P, Russell) often coincide with June/December witching

How to trade around expiry

1. Mark the third Friday on your calendar — know when expiry is
2. Expect unusual behavior into expiry, especially witching Fridays
3. Avoid fighting large open-interest strikes near the close
4. Roll positions early if you don't want to be exercised
5. Watch GEX (gamma exposure) for the day's volatility regime
6. Don't read post-expiry drift as signal — it's often just gamma rolling off

Caveats

• Pin and max-pain effects are real but modest; don't over-trade them
• Expiry effects are smaller in liquid, deep markets
• The same Friday can host index rebalances, adding flow unrelated to options

Practical steps

1. Track monthly and quarterly expiry dates
2. Flag the four quadruple-witching Fridays each year
3. Note large open-interest strikes for magnetism
4. Roll options you intend to keep a week before expiry
5. Treat unusual expiry-day moves as flow, not fundamental

Bottom line

Options expiry is a structural event that distorts price through dealer hedging. Quadruple witching concentrates that distortion four times a year. Trade knowing the calendar — or get pinned by it.