About Indices:
- Indices are a collection of single stocks;
- Indices are useful to monitor market movements;
- WEI is broken down by geography;
- S&P 500 - 500 public companies with the biggest market capitalizations in the U.S.;
- An index may be domiciled in one country, but companies contained therein may have revenues coming from many other countries*;
* Over a third of the revenues from the members of the main U.S. index come from outside the U.S.
Most common organizing principles for stock market indices:
- Company size;
- Industry;
- Country.
Extra:
- MEMB is a great function within the Bloomberg Terminal that provides a list of companies included in the selected index.