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!

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.

I remember when I was growing up, you would go to a bank to open a deposit, and they'd give you a toaster. A free toaster. These days, if you're a company, and you go to a bank, they could easily turn you away! They don't want your deposits anymore.

[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.

As we spend more, and as companies are pushed to invest, they say, "Hey wait a minute! There's more demand in the system. Let's invest more."

How long can interest rates stay negative? Think about this. Not only are you lending your money to governments, but you're paying them interest for the privilege of doing so.