Representatives from across South America will sign agreements on Sunday setting up a new regional bank, the Banco del Sur or Southern Bank.
The body is designed to supersede the World Bank and International Monetary Fund (IMF), seen by many as responsible for failed policies in the region.
Funded by regional powers such as Brazil, Argentina and Venezuela, it will aid economic and social projects.
Each member will have one vote, irrespective of its size or funding.
Set up by Brazil, Venezuela, Argentina, Uruguay, Paraguay, Ecuador and Bolivia, the Banco del Sur will have its headquarters in Caracas, with offices in Buenos Aires and La Paz.
The idea was born after what analysts say were the failed economic recipes suggested by the IMF and the World Bank.
"From a theoretical point of view it's necessary, it has been necessary for a long time," said Argentine economist Alan Cibils.
But he added: "From a practical point of view I would say I'm sceptical. It'll be very difficult to have an institution that operates with transparency and efficiency given the levels of corruption in the governments that are sponsoring this institution."
The agreements to formally set up the bank are being signed in Buenos Aires where regional leaders have gathered for Monday's inauguration of the new president of Argentina, Cristina Kirchner.
They hope to start with $800m and eventually gather $7bn, with funds to deal with natural disasters and develop joint scientific and economic projects across the region.
It sounds grand but the squabbles about just how it will operate have already begun.