Ask the Fool: What’s with the S&P 500 reorganization?

Ask the Fool Reorganizing the S&P 500 Q: I heard that the S&P 500 recently reorganized itself. What does that mean? -- A.B., Winona, Minn. A: The Standard & Poor's 500 index of 500 big companies is adjusted regularly, with some companies being removed from the index while others are added to replace them. For example, Twitter was added to the index in June to replace Monsanto, as Monsanto was being acquired by the German company Bayer and would no longer be a stand-alone company or s