Is this what market index value is and how market index value is calculated?

Question

So I think this is what I'm thinking of, I see that it says the market is up or down a certain percentage each day. This is calculating all the total combined values for all the stocks listed on that exchange, and then it is compared to the previous day to get the current days percent change up or down?

This formula is called market value ? or index value ?

Answer 1

The Dow and S&P 500 are calculated differently.  These explain how.

http://www2.standardandpoors.com/spf/pdf...

http://www.djindexes.com/mdsidx/index.cf...