I started tracking this in March 2016 using data from WSJ. Estimates fluctuate so we are watching the overall pattern and how price responds to levels. This is how my spreadsheet looks from April.

Date / SPX 12 month forward earnings estimate / Close SPX price / p/e ratio
4/01/2016 118.51 2072 17.49
4/08/2016 117.61 2047 17.41
4/15/2016 112.47 2080 18.50*
4/22/2016 117.50 2091 17.80
4/29/2016 117.01 2065 17.65
5/6/2016 116.95 2057 17.59
5/13/2016 116.15 2046 17.62
5/20/2016 117.21 2052 17.51
5/27/2016 118.26 2099 17.75
6/03/2016 117.86 2099 17.81
6/10/2016 116.97 2096 17.92
6/17/2016 115.90 2071 17.87
6/24/2016 113.63 2037 17.93

Aside from 4/15 the p/e has stayed in very tight range from 17.5 up to 18.0. Despite the drop last week, according to these estimates the p/e is actually higher! I'm not sure how these estimates work but there must be some currency factor involved to move that quickly. (I'm not sure about the *d week of 4/15; i cannot go back and check the data.)

No real change to Citigroup Economic Surprise Index - chopping below the zero line.

I have said all year that these two factors likely put a lid on upside, but also thought that we would probably see major levels for a big top. Brexit seems to have thrown that off.