In August, Exxon Mobil, once the largest publicly traded company in the world, was dropped from the Dow Jones industrial average after 92 years. Exxon's removal is emblematic of the changing profiles of energy companies. In 2008, oil and gas companies accounted for more than 15 percent of the S&P 500; today they make up only 2.3 percent. And, according to the Washington Post, five major tech companies—Alphabet, Amazon, Apple, Facebook and Microsoft—are each worth more than the top 76 energy companies put together.