The NYMO is a market breadth indicator that is based on the difference between the number of advancing and declining issues on the NYSE. When readings are +60/-60 markets are extended short-term.
The McClellan Summation Index is a long-term version of the McClellan Oscillator. It is a market breadth indicator, and interpretation is similar to that of the McClellan Oscillator, except that it is more suited to major trends. I believe readings of +1000/-1000 reveal markets as much extended.
The VIX is a widely used measure of market risk and is often referred to as the "investor fear gauge". Our own interpretation is highlighted in the chart above. The VIX measures the level of put option activity over a 30-day period. Greater buying of put options (protection) causes the index to rise.