I've been pointing to 18x forward earnings as resistance in each valuation post all year. As of last week that level was SPX 2121.

There is some fluctuation in the estimates each week that I am using from the WSJ. This week earnings estimates dropped a bit, so the P/E finished the week at 17.92.

This makes the 18x level lower, down to 2105. Potential support at 17x now 1988.

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Similarly Yardeni's report of the Citigroup Economic Surprise Index, while looking slightly better for a little while, has not changed its essential character from the start of 2015 - below the zero line.

Check the tag and you'll see I've consistently pointed out both factors as limiting upside, and we saw part of what that means on Friday with pro sellers hitting the 18x level on SPX before the market could test the highs.