What are the key differences between the S&P $500$ and the Dow Jones Industrial Average $($DJIA$)$ in terms of company representation and Index calculations? The S&P $500$ represents a much fewer number of companies and is weighted based on company stock prices, while the DJIA represents a much larger number of companies and its index is market cap weighted. The S&P $500$ represents a much larger number of companies and is weighted ba on company stock prices, while the DJIA represents much fewer companies and its index is market cap weighted. SET The S&P $500$ represents a much larger number of companies and is market cap weighted, while the DJIA represents much fewer companies and its index is weighted based on company stock prices.