The stock market is like an ocean of over 6,000 stocks moving simultaneously throughout the day. Rather than trying to track each stock individually, the Standard and Poor’s (S&P), Dow Jones Indices and MSCI developed the Global Industry Classification Standard (GICS) in 1999 as a way to track groups of stocks. These groups are organized into general categories known as stock market sectors.
Within the sectors are industry groups, which then are split into industries and then further divided into sub-industries. These classifications make it easier to track, compare and organize the performance of not only the companies within the categories but also the categories themselves. All publicly listed companies should fall into one of the 11 stock market sectors but only the major public companies are actually tracked and officially placed into the sectors and industries.
These market sectors help to comprise benchmark indices such as the S&P 500 Index, which is a widely accepted measure of the performance of the stock market and the economy. The S&P 500 contains the largest and most dominant businesses in the country.