market volatility index(The market volatility index is calculated based on option activity and is used as an indicator of investor sentiment, with high values implying pessimism and low values implying optimism. There are three volatility indexes in the Chicago Board Options Exchange which track the three main stock indexes: the VIX is the most widely used, tracking the S&P 500, but there also is the VXN which tracks the Nasdaq and the VXD which tracks the Dow Jones Industrial Average. Alex_Odeychuk)
