Divining the quad witching trading session

|By:, SA News Editor

Time to stir the brew. It's quadruple witching day, which refers to the simultaneous expiration of stock-index futures, stock-index options, single-stock futures and stock options, which can lead to higher volatility for markets and more trading volume.

The event happens four times a year - on the third Friday of March, June, September and December - but this time around the S&P Dow Jones predicts the rebalancing could force $23.1B of trades, up from around $18.6B a year ago.