Investors can gain exposure to vast investment opportunities through stock market sectors. The only question is what form their investment will take. The options are purchasing of individual stocks or buying specialized sector funds, such as exchange-traded funds (ETFs) or mutual funds that primarily hold stocks within a single sector. Investors interested in exposure to all sectors can consider a broad-based mutual fund or ETF like the S&P 500 Trust ETF (SPY). Who makes sure it’s all up to spec? There are 11 stock market sectors, according to the Global Industry Classification Standard, or GICS, which is an industry taxonomy developed in 1999 by MSCI and Standard & Poor's. The 11 stock market sectors are then sub-divided into 24 industry groups, 69 industries and 158 sub-industries into which all major public companies fit. Annual reviews are conducted by S&P Dow Jones Indices and MSCI to ensure that the structure remains f...