A $4 Trillion ‘Triple Witching’ Event Endangers Stock Market Calm

All week, stock traders have shrugged off everything from hot inflation data in the US to another recession-threatening hike in interest rates over in Europe.

Now comes a $4 trillion options event that has historically stoked turbulence, just as equities are mired in the most subdued trading in two years.

In a quarterly episode ominously known as triple witching, piles of derivatives contracts tied to stocks, index options and futures are scheduled to mature Friday — compelling traders en masse to roll over their existing positions or to start new ones. This time, it coincides with the rebalancing of benchmark indexes including the S&P 500, another catalyst for more share transactions.

Though the risk is sometimes overblown by Wall Street players, the options event has a reputation for causing sudden price moves. And the one in September has typically been followed by an equity swoon the ensuing week.

One player to watch: Dealers on the other side of options transactions who are obliged to buy and sell stocks to maintain a market-neutral stance. A shift in their stock exposure, known by esoteric concepts like gamma, was cited as fueling the August selloff and is now blamed for this month’s inertia.

Options referencing 3.9 trillion of equities expire on 15 Sep

Source: Asym 500