Nobel economist Paul Krugman slams Brazil and Argentina's joint currency plan, saying 'it's a terrible idea'

• Paul Krugman criticized Brazil and Argentina's plan to create a common currency for trade. 
• "It's a nice opportunity to apply the theory of Optimum Currency Areas — which tells us that it's a terrible idea," he said on Twitter.
• The plan could spread economic shocks between the countries who opt in, Krugman added.

The euro-like shared-currency project proposed by Brazil and Argentina is a "terrible idea", according to Nobel Prize-winning economist Paul Krugman.

A common currency would work for countries that are each other's top trading partners and are similar enough to avoid the threat of so-called "asymmetrical shocks", but the two South American nations don't fit the bill, according to him.