How to calculate P/E ratio for S&P500 sectors
For the S&P and many other indices (but not the DJIA) the index "price" is just a unitless number that is the result of a complicated formula.  It's not a dollar value.  So when you divide said number by the earnings/share of the sector, you're again getting just a unitless number that is incomparable to standard P-E ratios. In fact, now that I think about, it kinda makes sense that each sector would have a similar value for the number that you're computing, since each sector's index formula is presumably written to make all the index "price"s look similar to consumers.
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How to calculate P/E ratio for S&P500 sectors

### Response:
For the S&P and many other indices (but not the DJIA) the index "price" is just a unitless number that is the result of a complicated formula.  It's not a dollar value.  So when you divide said number by the earnings/share of the sector, you're again getting just a unitless number that is incomparable to standard P-E ratios. In fact, now that I think about, it kinda makes sense that each sector would have a similar value for the number that you're computing, since each sector's index formula is presumably written to make all the index "price"s look similar to consumers.