If you have information that a company is not as good as its stock market valuation, you don't have a way to sell that stock unless you already own it. And so that information doesn't get incorporated in the company's stock price as fast if you don't allow short selling.

I don't think the idea of requiring these to be only sold to people who have already own the bonds, in other words, this naked position that the Germans have recently put into their financial regulation and has been discussed here. I don't think that makes any sense.

Well if you've got information about a company, or you believe that a company is undervalued, you can go out and buy their stock and you can make some profit on it.

The collateralized debt obligation, the CDO, is a structure which allows you to more or less continuously choose how much risk you want to take in a whole batch of securities. And the reason why they got us into so much trouble is that it's hard to figure out how much risk you really are taking.

When large companies take on risk, then they impose risks on the rest of the system. And these are systemic risks and these systemic risks we never used to think were really that important, but as soon as we recognize how the financial sector - the risks the financial sector takes on can impact the entire global economy, we realize that those risks needed to be controlled for the social good.

So what is the role that credit default swaps can play in an economy? Well my feeling is that if these things actually will now be traded on either exchanges or some kind of central clearing, they are going to be a very good measure of the credit worthiness of different companies.

Risk managers and investment bankers and actually, all kinds of investors took on more risk than they expected. So there was a failure of risk management. There was a failure to recognize how much risk there was in some of these securities that people bought.