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.