The Dow Jones Industrial Average was established in 1896 with just 30 companies because it it was a lot of work to average 30 numbers back then. Charles Dow probably would have averaged a far larger number if calculators had existed. Today the Dow Jones Industrial Average is *still* an average of just 30 companiesβ share values, because β¨traditionβ¨, despite the existence of computers.
This is why I ignore the Dow Jones Industrial Average.