P/E ratio for the S&P500 index vs. the ETF?

[soupcxan]

I'm trying to figure out the correct P/E ratio for the S&P500 based on the last twelve months of earnings. The S&P website quotes 22.49 as of 5/31/08:

S&P | Indices > Equity Indices - S&P 500 - Month End Data

But given the declines in the market this year, that seems a little high. By comparison, Yahoo reports the P/E on the S&P500 ETF (SPY) at the same point in time to be 14.22. I imagine the ETF is going to be off a little due to expenses and dividends, but that is a sizeable discrepancy.

Meanwhile, Vanguard reports a P/E of 17.6 for its S&P500 index fund (VFINX) at the end of May:

https://personal.vanguard.com/us/funds/holdings?FundId=0040&FundIntExt=INT

Any thoughts on which number is correct?

 

[clifp]

I swear there must be as many P/E ratio for the S&P 500 as there are financial websites.
Digging around the standard poors I came across a bunch of different ratio with 16.5 being the current operating earnings, that roughly agree with the WSJ graph of SPX. Of course S&P 500 spreadsheet also had a number around 23, which was roughly the same John Mauldin was using on his website.



It seems to me there was Seeking Alpha article about this a while but I can not find it. I love an explaination a PE of 14-16.5 seems reasonable 23 sounds expensive!