The US equity market remains expensive, overbought and speculative. The total capitalization of the equity market hovers near all time high percentages of US GDP. And the P/E ratio of the S&P based on GAAP earnings shows that valuations have only been this high during stock market bubbles.
Compounding the problem is the fact that corporate margins are tracking at 60 year highs. Not only is this "as good as it gets", but any move towards long term average margins will make stocks appear that much more expensive on any earnings basis.
Also, current sentiment is near extremes. The NDR Crowd Sentiment Poll is above 70, evidence that investor sentiment hovers at overly optimistic levels. Margin debt is high, as