The purpose of this paper is to suggest a new theory of portfolio selection which is based on evolutionary reasoning in simple repeated market situations. According to this new point of view the ultimate success of a portfolio strategy is measured by the wealth share the strategy is eventually able to conquer in an evolutionary process of market selection. We identify a simple portfolio strateg...

We show how optimal saving in a two-period model is affected when prudence and risk aversion of the underlying utility function change. Increasing prudence alone will induce higher savings only if, for certain combinations of the interest rate and the pure time discount rate, there is distributional neutrality between the two periods. Otherwise, changes of risk aversion that affect the distribu...

This paper shows that the notions of prudence, temperance, edginess, and, more generally, risk apportionment of any degree are the consequences of the natural idea that the sensitivity to detrimental changes should decrease with initial wealth. In the setting of Epstein & Tanny (1980), this turns out to be equivalent to the supermodularity of the expected utility for some specific 4-state lotte...

In this paper we extend the results of recent studies on the existence of equilibrium in finite dimensional asset markets for both bounded and unbounded economies. We do not assume that the individual’s preferences are complete or transitive. Our existence theorems for asset markets allow for short selling. We shall also show that the equilibrium achieves a constrained core within the same fram...

Donors may often not be sure whether a recipient really deserves their help. Does this uncertainty deter generosity? In an experiment we find that, to the contrary, under most specifications of uncertainty, dictators give more, compared with the donation the same dictator makes to a recipient they know to have the expected value of the endowment with certainty. They are particularly concerned a...

This paper describes a pure-exchange, continuous-time economy with two heterogeneous agents and complete markets. A novel feature of the economy is that agents perceive some security returns as ambiguous in the sense often attributed to Frank Knight. The equilibrium is described completely in closed-form. After identifying agents as countries, the model is applied to address the consumption hom...

Ghirardato, Maccheroni, and Marinacci (2004) propose a method for distinguishing between perceived ambiguity and the decision-maker’s reaction to it. They study a general class of preferences which they dub invariant biseparable. This class includes CEU and MEU. This note presents some examples which illustrate their results. Keywords, Ambiguity, multiple priors, invariant biseparable preferenc...

In this paper we survey recent works on rational inattention (RI) in macroeconomics within the dynamic linear-quadratic-Gaussian (LQG) setting. We first discuss how RI affects consumption smoothness and sensitivity, precautionary savings, asset pricing, portfolio choice, and aggregate fluctuations in the univariate case. We then discuss the applications of RI to macroeconomic models of permanen...

Ambiguity preferences are important to explain human decision-making in many areas in economics and finance. To measure individual ambiguity preferences, the experimental economics literature advocates using incentivized laboratory experiments. Yet, laboratory experiments are costly and require a lot of time and administrative effort. This study develops an ambiguity preference survey module th...