After revising the current P/E ratio of the components of the S&P 500(PE: 36.7x) it seems to be slightly overvalued in spite of the good evolution of the US economy. Business are not making enought results therefore, the current prices don't fit the profits thought good profit evolution is forecasted . Pitch stocks with caution searching value if you aren't invested (and you want invest) and wait for those expected results if you are invested.