Not the original poster but I would point to the Shiller PE (i.e. CAPE) ratio as a useful indicator of potential over-valuation. The increasing cost required to

Not the original poster but I would point to the Shiller PE (i.e. CAPE) ratio as a useful indicator of potential over-valuation. The increasing cost required to make the same in earnings is disconcerting. https://en.wikipedia.org/wiki/Cyclically_adjusted_price-to-earnings_ratio https://en.wikipedia.org/wiki/Cyclically_adjusted_price-to-e... http://www.econ.yale.edu/~shiller/data.htm http://www.econ.yale.edu/~shiller/data.htm