Math Is Bad For Stocks

 | Jun 07, 2016 02:23PM ET

In recent years, equities have been carried higher by several compounding effects: economic growth, expanding profit margins and expanding multiples.

These three things, by definition, determine equity prices (if we assume that gross sales are tied to economic growth):

  • Price = Price/Earnings x Earnings/Sales x Sales

When all three are rising, as they have been, it's a strong elixir for stock prices. Which explains why stock prices are so high. But the devil is in predicting these components, of course -- no mean feat.

Yet we can make some observations. For some time, P/E ratios have been extremely high by historical measures, with the Shiller Cyclically-Adjusted P/E ratio (NYSE:CAPE) roughly doubling since the bottom in 2009. With the exception of the equity bubble in 1999-2000, the CAPE has not been much higher than it is now, at 26.4 (see chart). This should come as no surprise to anyone who follows markets regularly.

source Gurufocus

Recently sales have been declining. However, on a rolling 10-year basis, the rise has been reasonably steady as the chart below illustrates. Over the last 10 years, sales per share have risen about 2.85% per year.