You may not like it, but "quadruple witching" is destined to become a part of stock-market parlance. Everyone has heard of "triple witching," of course. That's the expiration of options on stocks, stock indexes and index futures. But on Friday, single stock futures contracts, which were launched just last month, also expired. While single stock futures are still a new product and open interest isn't terribly large at this point, some analysts said the addition had an impact on the market Friday. Diane Garnick, chief global strategist for State Street Global Advisors, said the derivatives market has been instrumental in sending the stock market higher. "Investors as a whole are net long puts, which means broker deals are short puts and to hedge their position, they needed to short index and single stock futures," she said. "Now as these puts expire, the dealers are coming back in and buying back those futures, so that's what's providing a lot of the support today." A put is an option to sell a stock at a certain price at a certain date in the future and is a bet that the price of the stock will go down. The brokers who sell these put options typically take offsetting positions (by shorting futures) to protect themselves if the stocks do in fact go down and they are forced to buy back shares from their customers at the strike price. When put options expire or are closed out, brokers are left with exposed short futures positions, which they must then cover. Garnick, who said she has been surprised at the volume and immediate acceptance of single stock futures, expects Friday to be the most heavily traded day of the quarter. Nasdaq volume hit 1.96 billion, while NYSE volume hit 1.78 billion.