Companies that market and distribute natural gas, the industry includes companies that engage in operating gas distribution systems, gas marketers that buy gas from the well and sell it to a distribution system, gas brokers or agents that arrange for the sale of gas over gas distribution systems operated by others, and companies engaged in transmitting and distributing gas to final consumers.

Companies that explore for crude petroleum and natural gas, drill oil and gas wells, and transport oil and gas to processing plants or other destinations; companies that provide oil and gas drilling equipment, and oil and gas field support services; companies that engage in the production of crude petroleum, the mining and extraction of oil from oil shale and sand, the production of natural gas, and the recovery of sulfur and hydrocarbon liquids from natural gas; companies that engage in the marketing and distribution of oil and gas products; companies that engage in the refining and processing of petroleum and the manufacturing of petrochemical products; companies that develop and operate alternative energy sources; and companies that invest in the oil and gas sector.

Companies that market and distribute natural gas and liquefied petroleum, including companies that operate gas distribution systems, gas marketers, gas brokers, and gas retailers.

Companies that explore for natural gas, drill gas wells, and transport gas to processing plants or other destinations; companies that engage in the production of natural gas and the recovery of sulfur and hydrocarbon liquids from natural gas; and companies that market and distribute natural gas and related products.