If prizes were being awarded for financial wizardry right now, some bright sparks at ABN Amro might be proudly waving their wands.

A few months ago the Dutch bank invented a product with the ugly name of constant proportion debt obligation (CPDO). So many other banks have since tried to copy this structure, that it has triggered sharp swings in the price of the credit derivatives that go into the CPDO pot – not to mention wild controversy about the merits, and dangers, of this product.