Standard & Poor’s decision to downgrade the creditworthiness of the US means there are now 17 countries to hold the coveted triple-A rating with the agency. There has been little suggestion from S&P that others, apart from New Zealand, are about to suffer the same fate but investors have their own opinions, judging by the fact that French debt is now three times more expensive to insure than T-Bills.

Credit default swaps offer protection over the possibility of a company or sovereign defaulting on its debt over a specified period of time. The prices of these contracts vary depending on the economic health of the debt issuer. The higher the price, the less faith the market has in the company or country's economic health.