Not just the day's numbers

What is the purpose of stock market indexes? If I look at the news and social media, the purpose is clearly to generate a number representing how the markets are doing today or how they did yesterday. Added to that is the widespread 'analysis' that tries to find clues as to why the markets rose or fell. If this is all that the indexes were good for, then they would be good for nothing. What can you, the investor, actually use an index for? It's important to recognise that stock market indexes do more than just provide a daily numerical snapshot of market performance. Every stock investor knows that stock market indexes are like a report card for the overall market. They show how the market is doing but not about how each stock is doing. If you only look at the index, you might miss some good investment opportunities. For example, the index might be going up, but some st