Press release



13 October 1999

The Royal Swedish Academy of Sciences awarded the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel, 1999, to

Professor Robert A. Mundell, Columbia University, New York, USA

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

Economic policy exchange rates and capital mobility
Robert Mundell has established the foundation for the theory which dominates practical policy considerations of monetary and fiscal policy in open economies. His work on monetary dynamics and optimum currency areas has inspired generations of researchers. Although dating back several decades, Mundell’s contributions remain outstanding and constitute the core of teaching in international macroeconomics.

Mundell’s research has had such a far-reaching and lasting impact because it combines formal – but still accessible – analysis, intuitive interpretation and results with immediate policy applications. Above all, Mundell chose his problems with uncommon – almost prophetic – accuracy in terms of predicting the future development of international monetary arrangements and capital markets. Mundell’s contributions serve as a superb reminder of the significance of basic research. At a given point in time academic achievements might appear rather esoteric; not long afterwards, however, they may take on great practical importance.

How are the effects of monetary and fiscal policy related to the integration of international capital markets? How do these effects depend on whether a country fixes the value of its currency or allows it to float freely? Should a country even have a currency of its own? By posing and answering questions such as these, Robert Mundell has reshaped macroeconomic theory for open economies. His most important contributions were made in the 1960s. During the latter half of that decade, Mundell was among the intellectual leaders in the creative research environment at the University of Chicago. Many of his students from this period have become successful researchers in the same field, building on Mundell’s foundational work.

Mundell’s scientific contributions are original. Yet they quickly transformed the research in international macroeconomics and attracted increasing attention in the practically oriented discussion of stabilization policy and exchange rate systems. A sojourn at the research department of the International Monetary Fund, 1961-1963, apparently stimulated Mundell’s choice of research problems; it also gave his research additional leverage among economic policymakers.

The Effects of Stabilization Policy
In several papers published in the early 1960s – reprinted in his book International Economics (1968) – Robert Mundell developed his analysis of monetary and fiscal policy, so-called stabilization policy, in open economies.

The Mundell-Fleming Model
A pioneering article (1963) addresses the short-run effects of monetary and fiscal policy in an open economy. The analysis is simple, but the conclusions are numerous, robust and clear. Mundell introduced foreign trade and capital movements into the so-called IS-LM model of a closed economy, initially developed by the 1972 economics laureate Sir John Hicks. This allowed him to show that the effects of stabilization policy hinge on the degree of international capital mobility. In particular, he demonstrated the far-reaching importance of the exchange rate regime: under a floating exchange rate, monetary policy becomes powerful and fiscal policy powerless, whereas the opposite is true under a fixed exchange rate.

In the interesting special case with high capital mobility, foreign and domestic interest rates coincide (given that the exchange rate is expected to be constant). Under a fixed exchange rate, the central bank must intervene on the currency market in order to satisfy the public’s demand for foreign currency at this exchange rate. As a result, the central bank loses control of the money supply, which then passively adjusts to the demand for money (domestic liquidity). Attempts to implement independent national monetary policy by means of so-called open market operations are futile because neither the interest rate nor the exchange rate can be affected. However, increased government expenditures, or other fiscal policy measures, can raise national income and the level of domestic activity, thereby escaping the impediments of rising interest rates or a stronger exchange rate.

A floating exchange rate is determined by the market since the central bank refrains from currency intervention. Fiscal policy now becomes powerless. Under unchanged monetary policy, increased government expenditures give rise to a greater demand for money and tendencies towards higher interest rates. Capital inflows strengthen the exchange rate to the point where lower net exports eliminate the entire expansive effect of higher government expenditures. Under floating exchange rates, however, monetary policy becomes a powerful tool for influencing economic activity. Expansion of the money supply tends to promote lower interest rates, resulting in capital outflows and a weaker exchange rate, which in turn expand the economy through increased net exports.

Floating exchange rates and high capital mobility accurately describe the present monetary regime in many countries. But in the early 1960s, an analysis of their consequences must have seemed like an academic curiosity. Almost all countries were linked together by fixed exchange rates within the so-called Bretton Woods System. International capital movements were highly curtailed, in particular by extensive capital and exchange rate controls. During the 1950s, however, Mundell’s own country – Canada – had allowed its currency to float against the US dollar and had begun to ease restrictions. His far-sighted analysis became increasingly relevant over the next ten years, as international capital markets opened up and the Bretton Woods System broke down.

Marcus Fleming (who died in 1976) was Deputy Director of the research department of the International Monetary Fund for many years; he was already a member of this department during the period of Mundell’s affiliation. At approximately the same time as Mundell, Fleming presented similar research on stabilization policy in open economies. As a result, today’s textbooks refer to the Mundell-Fleming Model. In terms of depth, range and analytical power, however, Mundell’s contribution predominates.

The original Mundell-Fleming Model undoubtedly had its limitations. For instance, as in all macroeconomic analysis at the time, it makes highly simplified assumptions about expectations in financial markets and assumes price rigidity in the short run. These shortcomings have been remedied by later researchers, who have shown that gradual price adjustment and rational expectations can be incorporated into the analysis without significantly changing the results.

Monetary Dynamics
In contrast to his colleagues during this period, Mundell’s research did not stop at short-run analysis. Monetary dynamics is a key theme in several significant articles. He emphasized differences in the speed of adjustment on goods and asset markets (called the principle of effective market classification). Later on, these differences were highlighted by his own students and others to show how the exchange rate can temporarily “overshoot” in the wake of certain disturbances.

An important problem concerned deficits and surpluses in the balance of payments. In the postwar period, research on these imbalances had been based on static models and emphasized real economic factors and flows in foreign trade. Inspired by David Humes’s classic mechanism for international price adjustment which focused on monetary factors and stock variables, Mundell formulated dynamic models to describe how prolonged imbalances could arise and be eliminated. He demonstrated that an economy will adjust gradually over time as the money holdings of the private sector (and thereby its wealth) change in response to surpluses or deficits. Under fixed exchange rates, for example, when capital movements are sluggish, an expansive monetary policy will reduce interest rates and raise domestic demand. The subsequent balance of payments deficit will generate monetary outflows, which in turn lower demand until the balance of payments returns to equilibrium. This approach, which was adopted by a number of researchers, became known as the monetary approach to the balance of payments. For a long time it was regarded as a kind of long-run benchmark for analyzing stabilization policy in open economies. Insights from this analysis have frequently been applied in practical economic policymaking – particularly by IMF economists.

Prior to another of Mundell’s contributions, the theory of stabilization policy had not only been static, it had also assumed that all economic policy in a country is coordinated and assembled in a single hand. By contrast, Mundell used a simple dynamic model to examine how each of the two instruments, monetary and fiscal policy, should be directed towards either of two objectives, external and internal balance, in order to bring the economy closer to these objectives over time. This implies that each of two different authorities – the government and the central bank – is given responsibility for its own stabilization policy instrument. Mundell’s conclusion was straightforward: to prevent the economy from becoming unstable, the linkage has to accord with the relative efficiency of the instruments. In his model, monetary policy is linked to external balance and fiscal policy to internal balance. Mundell’s primary concern was not decentralization itself. But by explaining the conditions for decentralization, he anticipated the idea which, long afterwards, has become generally accepted, i.e., that the central bank should be given independent responsibility for price stability.

Mundell’s contributions on dynamics proved to be a watershed for research in international macroeconomics. They introduced a meaningful dynamic approach, based on a clear-cut distinction between stock and flow variables, as well as an analysis of their interaction during the adjustment of an economy to a stable long-run situation. Mundell’s work also initiated the necessary rapprochement between Keynesian short-run analysis and classical long-run analysis. Subsequent researchers have extended Mundell’s findings. The models have been extended to incorporate forward-looking decisions of household and firms, additional types of financial assets and richer dynamic adjustments of prices and the current account. Despite these modifications, most of Mundell’s results stand up.

The short-run and long-run analyses carried out by Mundell arrive at the same fundamental conclusion regarding the conditions for monetary policy. With (i) free capital mobility, monetary policy can be oriented towards either (ii) an external objective – such as the exchange rate – or (iii) an internal (domestic) objective – such as the price level – but not both at the same time. This incompatible trinity has become self-evident for academic economists; today, this insight is also shared by the majority of participants in the practical debate.

Optimum Currency Areas
As already indicated, fixed exchange rates predominated in the early 1960s. A few researchers did in fact discuss the advantages and disadvantages of a floating exchange rate. But a national currency was considered a must. The question Mundell posed in his article on “optimum currency areas” (1961) therefore seemed radical: when is it advantageous for a number of regions to relinquish their monetary sovereignty in favor of a common currency?

Mundell’s article briefly mentions the advantages of a common currency, such as lower transaction costs in trade and less uncertainty about relative prices. The disadvantages are described in greater detail. The major drawback is the difficulty of maintaining employment when changes in demand or other “asymmetric shocks” require a reduction in real wages in a particular region. Mundell emphasized the importance of high labor mobility in order to offset such disturbances. He characterized an optimum currency area as a set of regions among which the propensity to migrate is high enough to ensure full employment when one of the regions faces an asymmetric shock. Other researchers extended the theory and identified additional criteria, such as capital mobility, regional specialization and a common tax and transfer system. The way Mundell originally formulated the problem has nevertheless continued to influence generations of economists.

Mundell’s considerations, several decades ago, seem highly relevant today. Due to increasingly higher capital mobility in the world economy, regimes with a temporarily fixed, but adjustable, exchange rate have become more fragile; such regimes are also being called into question. Many observers view a currency union or a floating exchange rate – the two cases Mundell’s article dealt with – as the most relevant alternatives. Needless to say, Mundell’s analysis has also attracted attention in connection with the common European currency. Researchers who have examined the economic advantages and disadvantages of EMU have adopted the idea of an optimum currency area as an obvious starting point. Indeed, one of the key issues in this context is labor mobility in response to asymmetric shocks.

Other Contributions
Mundell has made other contributions to macroeconomic theory. He has shown, for example, that higher inflation can induce investors to lower their cash balances in favor of increased real capital formation. As a result, even expected inflation might have a real economic effect – which has come to be known as the Mundell-Tobin effect. Mundell has also made lasting contributions to international trade theory. He has clarified how the international mobility of labor and capital tends to equalize commodity prices among countries, even if foreign trade is limited by trade barriers. This may be regarded as the mirror image of the well-known Heckscher-Ohlin-Samuelson result that free trade of goods tends to bring about equalization of the rewards to labor and capital among countries, even if international capital movements and migration are limited. These results provide a clear prediction: trade barriers stimulate international mobility of labor and capital, whereas barriers to migration and capital movements stimulate commodity trade.

Further Reading

Additional background information (pdf)

Mundell, R.A. (1961), “A Theory of Optimum Currency Areas”, American Economic Review 51: 657-665.

Mundell, R.A. (1963), “Capital Mobility and Stabilization Policy under Fixed and Flexible Exchange Rates”, Canadian Journal of Economics 29: 475-485.

Mundell, R.A. (1968), International Economics (New York: MacMillan).

Robert A. Mundell was born in Canada in 1932. After completing his undergraduate education at the University of British Columbia he began his postgraduate studies at University of Washington and continued it at M.I.T. and London School of Economics. Mundell received his Ph.D. from M.I.T. in 1956 with a thesis on international capital movements. After having held several professorships, he has been affiliated with Columbia University in New York since 1974.

Professor Robert A. Mundell
Economics Department
Columbia University
1022 International Affairs Building
420 West 118th Street
New York, NY 10027

The amount of the Prize Award is SEK 7, 900, 000


To cite this section
MLA style: Press release. Nobel Prize Outreach AB 2023. Mon. 4 Dec 2023. <>

Back to top Back To Top Takes users back to the top of the page

Streams during Nobel Week

Watch the 2023 Nobel Prize lectures, the Nobel Prize Concert, Nobel Week Dialogue, the prize award ceremonies in Oslo and Stockholm and Nobel Peace Prize Forum here at
Watch lectures and award ceremonies

Explore prizes and laureates

Look for popular awards and laureates in different fields, and discover the history of the Nobel Prize.