The most common sectors in the U.S. stock market include consumer cyclicals, consumer staples, energy, financials and health care. Industrials, technology and utilities are also popular, explains Investopedia. As of November 2015, financials and technology are the largest American stock market sectors, according to market cap data compiled by Morningstar.
Sectors are broad classifications encompassing several related industries, notes Investopedia. Companies within a sector tend to perform similarly, so investors can manage risk by investing in a diverse portfolio that encompasses most or all of the market's sectors.
Investors can bet on the performance of entire sectors by purchasing exchange-traded funds, reports Investopedia. This practice may be useful if an investor expects demand to increase in a certain sector but is unable or unwilling to predict which companies would ultimately capture that demand.