Skip to content
1999Sveriges Riksbank Prize · Information, finance, and development

Robert Mundell

Citation: For his analysis of monetary and fiscal policy under different exchange rate regimes and his analysis of optimum currency areas.

The key idea

Optimum currency area: countries with similar shocks, labour mobility, and fiscal transfers can share a currency. The 'impossible trinity': you can't simultaneously have a fixed exchange rate, free capital mobility, and independent monetary policy — pick two.

The explanation

Mundell's 1961 paper laid the theoretical basis for the euro. His Mundell-Fleming model showed how fiscal and monetary policy effects depend on the exchange-rate regime. The impossible trinity (or 'trilemma') is the single most-quoted fact in open-economy macro.

Why Africa should care

Mundell's framework is the analytical basis of the EAC monetary union debate, the WAEMU/CEMAC CFA franc zones, and the proposed ECOWAS Eco. Whether any African region is an OCA in Mundell's sense remains contested. The impossible trinity explains why African central banks repeatedly fail to defend pegs (Nigeria, Ghana, Egypt cycles): they cannot simultaneously have free capital flows AND a peg AND independent rate-setting.

How to use it

When a country promises an exchange-rate peg, free capital flows, and independent inflation-targeting, count to two. The third will break, usually at the worst time.

Canonical works

  • Robert A. Mundell (1961) "A Theory of Optimum Currency Areas" American Economic Review
  • Robert A. Mundell (1963) "Capital Mobility and Stabilization Policy under Fixed and Flexible Exchange Rates" Canadian Journal of Economics and Political Science
Official Nobel Foundation page ↗