Triple Witching Day is the third Friday in March, June, September and December, which tends to see heavy volume, as it is the last trading day before the quarterly expirations of stock options, index options, and futures. In recent years, “quadruple witch” has come to replace the term “triple witch” because the newer single stock futures also cease trading at that time. June 19 is the next “witching” expiration and might help explain some of the volatility seen in the equity market Monday and Tuesday.