The Dow Jones measures the performance of 30 of the largest and most influential companies in the United States. This index only represents about 25% of the total stock market’s value, so it isn’t quite as adequate in portraying the entire market as a whole like the S&P 500 is. This index is more of a benchmark of investor attitude toward well known, large-cap companies that are known for consistent returns and stable investments. These types of stocks are typically referred to as blue chips.