Index funds are somewhat higher risk, always best to diversify. Yadda yadda...
interested in your ' somewhat '. if you can show an article, specific to the S and P
here is what I go by:
The S&P 500 stock market index, maintained by S&P Indices, comprises 505 common stocks issued by 500 large-cap companies and traded on American stock exchanges (including the 30 companies that compose the Dow Jones Industrial Average), and covers about 80 percent of the American equity market by capitalization. The index is weighted by free-float market capitalization, so more valuable companies account for relatively more of the index.
IOW, 505 of the biggest and likely the best. or more " valuable co's "