The Calculation Behind the Dow To better understand how the Dow changes value, let's start at its beginnings. When Dow Jones & Co. first introduced the index in the 1890s, it was a simple average ...

Now, let's say that Apple releases some incredibly positive news tomorrow, and its shares jump by 20%, or to $113.62. This would raise the price-weighted average to $64.53, a 10.8% jump.