Dow Index ComponentsThe DJIA launched in 1896 with just 12 companies, primarily in the industrial sector. They included railroads, cotton, gas, sugar, tobacco, and oil. The index grew to 30 components by 1928. Since then, it's changed many times—the very first came three months after the 30-component index launched. The first large-scale change was in 1932 when eight stocks in the Dow were replaced.11121 The Dow is reevaluated on a regular basis. Companies are replaced when they no longe...