Once you start moving [market] lower, then you trigger of all sorts of things. You trigger people who have to sell because they're over-levered. So they sell their winners and their losers. They're just trying to raise cash. So, what you then get is spreading malaise throughout the global markets.

The one instrument that has relative political autonomy is monetary policy. Central banks do not need to go to Congress to get approval for an interest rate hike.

It is hard to imagine that, having downgraded the US, S & P will not follow suit on at least one of the other members of the dwindling club of sovereign AAAs. If this were to materialise and involve a country like France, for example, it could complicate the already fragile efforts by Europe to rescue countries in its periphery.

The once-unthinkable loss of the AAA rating will constitute a further hit to already fragile business and consumer confidence.

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.

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."

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.