My downside target for the S+P is 1325, written on my whiteboard the day after the Dow -500 crash a couple of weeks ago. Let's see how close I get.
My random thought here though is that holding the companies in the S&P500 in a static way is sort of a losing proposition. Almost none of the large cap companies in the index 20 years ago are still in the index... so what are you really buying? I think its the methodical rotation that is the value. Momentum stocks that are just starting to get huge get added to the index and you are a buyer there. Stocks that are getting killed and aren't working get removed from the index and you are a seller.
I wonder if someone has looked at a trading strategy in which you long stocks that enter the S&P and short stocks that leave it, over a certain well defined time period. You never actually hold the stocks that stay in the index.