The tech giants have replaced the energy giants such as ExxonMobil, BP, Gazprom, PetroChina, Chevron, and Shell ("Big Oil") from the first decade of the 21st century at the top of the NASDAQ stock index. They have also outpaced the traditional big media companies such as Disney, Warner Bros. Discovery, and Comcast by a factor of 10.[56] In 2017, the five biggest American IT companies had a combined valuation of over $3.3 trillion, and made up more than 40 percent of the value of the Nasdaq 100.[2] It has been observed that the companies remain popular by providing some of their services to consumers for free.[58]