Companies issuing bonds denominated in euros are amending the documentation accompanying the debt in a bid to protect themselves against future litigation that could arise from a break-up of the eurozone.

Brazilian energy group Petrobras filed details of a €2.5bn investment grade-bond with the US Securities and Exchange Commission on December 7 and in the deal's prospectus the company detailed re-denomination risk. It warned that some countries could exit the euro and revert to their former currency and highlighted the possibility that the euro could dissolve altogether, which would devalue the bond.