$6.8 trillion worth of options on stock indexes, ETFs, equity index futures, and individual stocks are set to expire during today's trading session. This is potentially the biggest “triple witching” OpEx on record, according to SpotGamma estimates. It will also be the first monthly post-holiday OpEx in at least 25 years. Furthermore, ~$4.5 trillion in notional value of expiring options is tied to S&P 500 index options. ~$1.0 trillion worth of options expiring are tied to single stocks. It's a big day. (S&P500) 🇺🇸