By TheStreet Staff What Is Triple Witching Day?Triple witching sounds like something from a horror movie, but it’s actually a financial term. Options and derivatives traders know this phenomenon well because it’s the day when three different types of contracts expire. It happens only once a quarter and can cause wild swings in volatility, as large institutional traders roll over futures contracts to free up cash. Doing so creates a ton of increased volume—sometimes 50% higher than average, especially in the last trading hour of the day—but individual investors needn’t feel spooked. In fact, so…