Triple Witching Day: How To Take Advantage Of It In Practice

 | Sep 15, 2019 03:06AM ET

Four times a year on the third Friday of March, June, September and December, contracts for stock index futures, stock index options and equity options expire concurrently. Derivatives contracts are not only expiring in the US on these days, but also at a number of international futures exchanges, such as for instance Eurex in Europe.

At specific times on this Friday reference prices are determined, which are then used to value and settle expiring futures and options contracts.

Triple witching days often generate increased trading activity, as dealers either close out or roll over contracts. Manipulation has also been detected around reference periods, with prices being driven close to desired levels (“pinning”). After all, the reference price is decisive in determining profits and losses in expiring options and futures.

September 20 2019: the next big expiration date lies directly ahead!

On September 20 it will happen again: many derivatives contracts will expire at the same time. How does this impact stock prices?

While most investors, pundits and academic studies are focused on triple witching day itself, we want to examine a period of several trading days before and after the expiration date.

The chart below illustrates the average move in the S&P 500 Index in the 15 trading days before and after triple witching day. The calculation is based on data of the past fifteen years, which include a total of 59 triple witching expiration days. The horizontal axis shows the number of days before and after the event, the vertical axis the average price move in percentage points.

Average price move of the S&P 500 Index in the 15 days before and after triple witching day, based on 59 events between 2004 and 2019