Price weighted equity indices. Now, despite being probably, the first type of index ever created price weighted indices are no longer commonly used. Weighting is calculated, it's fairly simple. It's just the stock price of each individual company divided by the sum of all the stock prices within the index. So what does this result in? Well, regardless of the issuing company's actual size, or the number of shares that it has outstanding, if one of the higher priced stocks within the index has a large price increase the index is more likely to increase even if the other stocks in the index with lower prices decline in value at the same time. The Dow Jones Industrial Average is the most well known price weighted index, and it's used that methodology since inception and it's been around for over a hundred years, and it's one of our oldest indices. Now, the main advantage of a price weighted index is that it's simple. It's simple not only to calculate, but understand and create. Now, the main disadvantage of a price index is that, what we've already discussed, is that it's solely based on price. And price alone does not speak to the value of a company and therefore, it's less likely to give us a true gauge of overall market movement. And lastly, another negative is that corporate actions, like stock splits that result in arbitrary changes in price, and in therefore, weightings really have nothing to do with the change in value of a specific company.