With investing, group think can sink you. If that sounds like a reason to always be contrarian, it's not. If you join the herd that is pushing up prices, you'll benefit from the rise. But if you hang around too long and the party ends in a hurry, you'll emerge from the broom closet to find broken furniture and capital loss.

The media fuels all of this by picking up a theme and running with it. Today it's the "reach for yield", most definitely. Big themes of the past made sense at the time but the fundamentals changed course or the bubble popped. Smart Investor looks at what's gone before (the BRIC economies, Asian tigers and internet stocks) and how we should think about some of the big themes of today (yield, internet stocks and infrastructure).