The Double Illusion

When Charles Dow formulated the initial Dow index of 30 companies, it's the same Dow index you have today. However, there is not one constituent in the Dow today from 130 years. So people like all, I mean, some of the greatest economic thinkers, Nobel laureates, will make this error. And what they do is they'll say the value of the index has gone up this much over this many years. But the problem is that the index from 100 years ago was an entirely different group of stocks.