The Dow and S&P finished 2013 at record highs. Many critics expect the markets to continue to rise, while others claim we are in a bubble that’s about to pop. Let's look at the fundamentals.
— Aswath Damodaran, Leading Authority on Valuation, Nia Creator
The thing about bubbles throughout all of history is that they are almost impossible to see looking forward and are only truly visible retrospectively. One can speculate asset bubbles but if we truly knew then it would be a lot easier to get rich quickly or prevent a major loss. That said, current growth rates do not seem to be sustainable.