The ‘triple-witching hour’ is drawing near.

Traders and investors are poised for a potentially tumultuous trading session this Friday when “triple-witching hour” comes around. Wall Street calls it the triple-witching hour when, once every three months, time runs out for investors to cash in on three different stock market-linked investment instruments. In the past that has caused huge swings in stock prices. Futures contracts on stock indexes, options on stock indexes and options on stocks are the three instruments. Stock indexes are based on one of several stock market indicators such as the Standard and Poor’s 500.