I completely agree the current irrational exuberance in stock markets is caused by the artificially depressed yields on bonds - it is yet another unintended con

I completely agree the current irrational exuberance in stock markets is caused by the artificially depressed yields on bonds - it is yet another unintended consequence of QE. You haven't mentioned risk though - this is a very risky game and the more mispriced assets get the riskier it is. What happens when interest rates rise?