In the spirit of better investing, and in celebration of the first annual Worldwide Invest Better Day (WWIBD) coming up on September 25, Motley Fool analysts will be answering user- and reader-submitted questions leading up to the big event. "Ask a Fool" anything, and we'll do our best to help you invest better.

The S&P 500 (INDEX: ^GSPC) is a capitalization-weighted index whose components are weighted by the total market value of outstanding shares. Because it's weighted this way, companies that are disproportionately larger -- like Apple (NASDAQ:AAPL) and Exxon (NYSE:XOM) -- have the most influence over the index, while those on the smaller end, like MAKO Surgical (UNKNOWN:MAKO.DL) and First Solar (NASDAQ:FSLR), have a much lower weighting. In the following video, Fool.com analyst Austin Smith goes over everything that investors need to know about the S&P 500.

 

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