I generally do not like to propose bans. But I cannot understand why we are still allowing the trade in credit default swaps without ownership of the underlying securities. Especially in the eurozone, currently subject to a series of speculative attacks, a generalised ban on so-called naked CDSs should be a no-brainer.

Naked CDSs are the instrument of choice for those who take large bets against European governments, most recently in Greece. Ben Bernanke, the chairman of the Federal Reserve, said last week that the Fed was investigating “a number of questions relating to Goldman Sachs and other companies in their derivatives arrangements with Greece”. Using CDSs to destabilise a government was “counter-productive”, he said. Unfortunately, it is legal.

CDSs are over-the-counter contracts negotiated by two parties. They offer the buyer insurance on a bundle of underlying securities. A typical bundle would be €10m worth of Greek government bonds. To insure against default, the buyer of a CDS pays the seller a premium, whose value is denoted in basis points. Last Thursday, a CDS contract on five-year Greek bonds was quoted at 394 basis points. This means that it costs the buyer €394,000 per year, for five years, to insure against default. If Greece defaults, the buyer gets €10m, or some equivalent. What constitutes default is subject to a complicated legal definition.