Roberto Serrano, winner of the King of Spain Prize in Economics

Roberto Serrano is one of the world’s leading economic theorists. His achievements are exceptional in any case. But given that he is blind, they border on the incredible

Eric Maskin, Nobel laureate in Economics, 2007

Every two years, the King of Spain Prize in Economics is awarded to a Spanish or Latin American economist in recognition of their achievements. Established by the Fundación José Celma Prieto in 1986, it is one of Spain’s most prestigious accolades in the social sciences. The selection panel is presided by the Governor of the Banco de España, and the prize is presented by King Felipe VI himself at our headquarters. For its twentieth edition, the award has been given to the Spanish economist Roberto Serrano, Professor of Economics at Brown University, in recognition of his significant contributions to both economic theory and game theory and his extraordinary personality.

Born in Madrid, Roberto Serrano graduated from Complutense University in 1987 and obtained a PhD in Economics from Harvard in 1992. His thesis was supervised by three prominent economic theorists: Andreu Mas-Collell (one of the first winners of the King of Spain Prize, in 1988), Eric Maskin (Nobel laureate in Economics in 2007) and Jerry R. Green. Serrano went on to join the Faculty at Brown University, where he became a full professor in 1997, at the age of just 33.

How has Serrano contributed to economics?

Serrano defines himself as an economic theorist. Economic theory works with abstract, mathematical models that seek to shed light on significant economic problems that could affect individuals, firms or countries (see Figure 1). Serrano takes a microeconomist’s approach: drawing on the behaviour of individual agents, he resolves the problems posed and then aggregates the conclusions for the corresponding group, be it consumers, workers, investors, firms or countries.

Figure 1
GAME THEORY WITHIN ECONOMICS

SOURCES: Banco de España, Wikipedia, Economipedia.

Microeconomics is the key theoretical tool of economics and determines how economists think. But it has a lower profile than macroeconomics (which involves large magnitudes and dominates the economic news), and economists who work in “micro” (as it is known in the field) also tend to receive less attention and acknowledgement, even from their fellow economists. This prize therefore pays tribute to micro’s importance in the field of economics.

Roberto Serrano is a world authority on non-cooperative game theory, in which each player makes their decisions separately and considers only their own personal gain

Within microeconomics, Serrano is recognised as a world authority in game theory, which is the study of strategic decisions made by individuals – or “players” – in situations where the outcome for each participant depends on the decisions of others. While this might all sound an amusing pastime, the models involve highly complex mathematics. Some of them are well known to the public, such as the prisoner’s dilemma, a non-cooperative game in which each player makes their decisions separately and considers only their own personal gain. 

This is Roberto Serrano’s area of expertise, where he has pushed the boundaries of knowledge. What have been his main contributions?

Economic models are resolved by deriving the (mathematical) equilibrium using hypotheses or assumptions about agents’ behaviour. There are two key assumptions:

1. Shared rationality: all individuals make the best decision possible based on their preferences and the information and resources available, and this is common knowledge to all the ‘players’.
2. Rational expectations, which mean that all agents, using all the available information, have the same expectations.

But what happens when these assumptions are not fulfilled? Well, equilibrium and its solution become more complicated, and the outcomes are not the same.

Serrano has approached these questions in the context of non-cooperative games. Specifically, he has worked on the design of mechanisms (rules or strategies) that steer players, without cooperating, towards behaviour that yields the best outcome for all, both when the players have no rational expectations and when they are not rational.

Another significant contribution by Serrano has been in the measurement of “riskiness”. The riskiness index he developed in 2008 with his namesake (and Nobel laureate) Robert Aumann is founded on several basic microeconomic principles applied to risk, and is the only one that satisfies all these principles. In a recent paper, he used this index to compare the riskiness of different cryptocurrencies with stock market risk.

A wonderful personality

These papers are included, along with others by Serrano, in the list provided in Table 1. In total, he has published over 80 papers in academic economics journals, with many appearing in the top economics journals, the goal of every economist (and something Serrano himself dubs Top5itis). But this is not what he values most: his primary concern is improving our understanding of economic reality and, therefore, of society itself. His specific goal is to better understand market mechanisms and economic agents’ incentives, to help design policies that improve society.

He has published papers in the top academic economics journals and has written two textbooks on microeconomics that are used in universities around the world

Table 1
SELECTION OF PAPERS BY ROBERTO SERRANO

Paper	Journal and year of publication	Co-author(s)	Contribution
"An Economic Index of Riskiness"	Journal of Political Economy, 2008	R. Aumann	Index of riskiness that satisfies several basic macroeconomic principles or axioms
"Level-k Mechanism Design"	Review of Economic Studies, 2019	G. De Clippel R. Saran	Implementability of rules in the presence of irrational agents
"On the Failure of Core Convergence in Economies with Asymmetric Information"	Econometrica, 2001	R. Vohra O. Volij	In economies with asymmetric information, the competitive equilibrium convergence theorem does not hold
"Multilateral Bargaining"	Review of Economic Studies, 1996	V. Krishna	Single equilibrium with multilateral bargaining based on alternating offers
"Comparative performance of cryptocurrencies through the Aumann-Serrano economic index of riskiness"	Annals of Operations Research, 2025	T. Yamawake J. Sheeley J. Hodoshima	Compares the riskiness of several cryptocurrencies with stock market risk
"Rationalizable Implementation of Correspondences"	Mathematics of Operations Research, 2019	T. Kunimoto	Characterisation of rules under the assumption of rationality, but without rational expectations
"Top5itis"	Economics Bulletin, 2018		A critique of academic economists’ obsession with the Top 5 journals
"Sixty-seven years of the Nash program: time for retirement?"	SERIEs, Journal of the Spanish Economic Association, 2021		Summary of the Nash research programme

SOURCE: Brown University.
NOTES: Professor Serrano’s own selection. The journals in which the first four papers appear are listed among the Top 5 journals in most categories.

In keeping with this idea, teaching and publishing are also essential to him. He has authored two textbooks, on intermediate microeconomics and welfare economics, which are widely used in universities around the world. Roberto Serrano is also an excellent professor held in high esteem by his students. He has received several teaching awards at his university and in 2012 was named one of the Best 300 Professors in the United States.

What makes these achievements by Roberto Serrano so exceptional and inspiring is that he began to lose his sight during adolescence and eventually became blind. Thanks to his determination and the support of his father, Carlos, he was able to complete his university studies with excellent grades. Imagine the dedication from his father, who was not an economist, but continued helping him as the mathematics became increasingly complex. Indeed, Carlos Serrano was more than worthy of the tribute the Complutense University paid to him in 2005, in the presence of his son. Fourteen years later, Roberto himself received an honorary degree from his alma mater.

Serrano’s pursuit of excellence, intellectual ability and speciality remind us of John Nash, one of the fathers of game theory and Nobel laureate in Economics in 1994. Does his name ring a bell? He was played by Russell Crowe in the film “A Beautiful Mind”, which won the Oscar for Best Picture in 2002.

Enrique Alberola

• Adviser and Chief Editor of BE Blog