The famous investor Warren Buffett had described them as financial “weapons of mass destruction”. “CDS”, for Credit Default Swap, are used to hedge once morest the risk of default of a bond of a country or a company. During the euro crisis, they were widely used by speculators to bet on the default of Greece in particular. However, instead of using them as insurance, these moderately well-meaning investors bought them “naked”, that is to say without even holding the debt.