In the latest look at the underlying components of the S&P 500 ordered by largest market capitalization, MGM Resorts International (MGM) has taken over the #344 spot from Seagate Technology Holdings PLC (STX), according to The Online Investor. Click here to find out the top S&P 500 components ordered by average analyst rating » Market capitalization is an important data point for investors to keep an eye on, for various reasons..