The energy sector is one of the 12 stock market sectors and is made up of companies that are involved in the exploration, production, refining, and sale of energy resources such as oil and natural gas, as well as companies that provide services to these industries. Some of the world's largest energy companies, such as Exxon Mobil (XOM) and Chevron, are part of the energy sector (CVX).

Rather than investing in individual stocks in the energy sector, ETFs can provide investors with low-cost, diversified access to the sector. There are 55 energy ETFs traded in US markets. The Energy Select Sector SPDR (XLE), with $37 billion in assets under management, is a large and popular energy ETF.