The theory is that if you take interest rates negative, people are going to say, "That's a silly game! I'm not going to lend my money to governments who want me to pay them. I am going to go into the stock market where I can get positive returns!"

Investors have to ask themselves two questions. How much can we grow our investments? And, can we afford our mistakes?

If you happen to be the only one with negative interest rates, you also weaken your currency, which means you make your exports more competitive.

We normally think if you're going to lend someone money, you should get some reward for doing this. In Europe, it's a tax!

Investors should invest on what they know. The biggest mistake is to invest on what they don't know.

[When] the market is trying to get to terms with, first, lower global growth, particularly out of emerging markets and China. And, second, the market is worried the central banks have run out of ammunition. So put these two things together, and then investors are repricing the market lower.

Most people are under exposed to global assets, including foreign stocks, bonds and currencies.