The article creates a way to measure how concentrated and vertically integrated different parts of a market are. It examines how upstream and downstream companies make deals and if they are part of the same company. By looking at this, the article creates a new index, the vertical Hirschman-Herfindahl index, that shows how competitive each part of the market is and if companies in it are joined together. This index helps us see how much the vertical chain is distorted due to market concentration and integration. It also helps us understand the effects of competition in different parts of the market and allows us to set a specific limit to check if a merger between companies in different parts of the market is acceptable.