Yields equalize in low volatility

Fed Warns "Equity Prices Are High", Sees Low Volatility As A "Risk To Financial Stability"

When there is little risk, yields tend to equalize across asset classes (future option pricing and a few other economic theorems show this and it is a generally accepted fact). 

The PE ratio, inverted is about 3.5%, but the one year treasury is 1.2%.  If volatility is low then take the stock market over the bond market.

The problem is volatility can return fairly fast and the exits from the trading pit gets jammed.