The seignorage rights have been estimated by Willem Buiter of Citibank and Huw Pill of Goldman Sachs, working independently, to be worth between €2-3 trillion, because they will yield more as the economy grows and interest rates return to normal. A Special Purpose Vehicle (SPV) owning the rights could use the ECB to finance the cost of acquiring the bonds without violating Article 123 of the Lisbon Treaty.