If I have a stock, we say MSFT, and I want to find its corresponding market index - how do I do this?
I thought I needed to start by finding out which index the stock, in this case MSFT, is included in and from there I know which is its market index. However, I have discovered that it is very difficult to find a answer to which index a certain stock belongs to and it also seems that some belong to several indices.
So, how do you really find the corresponding market index of a stock? And if it belongs to several indices, which one should I use if I want to check the market index for a specific stock?
As an example, here I found a list of which index memberships MSFT belongs to. But if I want to analyze MSFT corresponding market index - which one should I download data from?