Working papers

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Departments: Economics & Decision Sciences

This paper analyzes, empirically and theoretically, the link between capital inflows and the quality of economic institutions. Starting with the example of Southern European countries (Spain, Portugal, Italy and Greece), we show that they experienced a significant decline in the quality of their institutions in the run-up to the euro currency, a period of cheap external funding and large capital inflows. We confirm this joint pattern of capital flows and institutional decline in a large panel of countries since the mid-1990s. We then develop an open-economy model of the "soft budget constraint" syndrome wherein persistently cheap funding from abroad (i) raises the prevalence of extractive projects and (ii) expands their support by the (benevolent) government ex post. While the government may in principle limit the prevalence of extractive projects ex ante, we show that the incentives to do so is limited when foreign borrowing is cheap.

Keywords: Institutions, current account


Departments: Economics & Decision Sciences

This paper shows that bailouts of private agents can optimally take the form of the purchase of a defaulting asset, even if this also means paying off external asset holders. When anticipated, this form of bailouts leads to an endogenous implicit guarantee, where even an intrinsically worthless asset may be traded at a positive price. In the presence of borrowing constraints and imperfectly observable private liquidity needs, direct transfers are imperfect so that, when more constrained agents are also more exposed to a given asset, the compensation through asset purchases becomes optimal. I then show that this possibility of implicit guarantee is amplified by other frictions as risk-shifting and ultimately leads to a coordination problem for selecting stores of liquidity. Finally, I derive policy implications for financial regulation and international capital flows.

Keywords: Implicit guarantees, bailouts, intrinsically worthless assets


Departments: Economics & Decision Sciences, GREGHEC (CNRS)

We revisit well-known models of learning in which a sequence of agents make a binary decision on the basis of a private signal and additional information. We introduce efficiency measures, aimed at capturing the speed of learning in such contexts. Whatever the distribution of private signals, we show that the learning efficiency is the same, whether each agent observes the entire sequence of earlier decisions, or only the previous decision. We provide a simple necessary and sufficient condition on the signal distributions under which learning is efficient. This condition fails to hold in many prominent cases of interest. Extensions are discussed.


Departments: Economics & Decision Sciences, GREGHEC (CNRS), Finance

Equity crowdfunding has recently become available and is quickly expanding. Concerns have been raised that investors ('backers') may be following the crowd 'too much' and making investments ('pledges') based on past investments rather than private information. We construct a model of equilibrium rational herding where uninformed investors follow signals generated by in formed investors with private information and a public belief generated by all past pledges. We show that large investments provide positive public information about the project's quality, whereas periods of absence of investment provide negative information. An information cascade is shown to occur only if not enough positive signals are generated. We then empirically analyse a large number of pledges from a leading European equity crowdfunding platform. We show that a pledge is strongly affected by both the size of the most recent pledge, and the time elapsed since the most recent pledge. For pledges that are not adjacent in the order of arrivals, the correlation between their sizes is still positive, but after being separated by two or more intervening pledges the correlation is no longer statistically significant. The effects are strongest for less-informed investors, and in some specifications the effects are strongest at the early stage of a campaign. We find similar results in IV analysis. Results are consistent with our model and inconsistent with some alternative models

Keywords: Equity Crowdfunding, Herding


Departments: Economics & Decision Sciences, GREGHEC (CNRS)

We consider a Bayesian persuasion problem where the persuader and the decision maker communicate through an imperfect channel which has a fixed and limited number of messages and is subject to exogenous noise. Imperfect communication entails a loss of payoff for the persuader. We establish an upper bound on the payoffs the persuader can secure by communicating through the channel. We also show that the bound is tight: if the persuasion problem consists of a large number of independent copies of the same base problem, then the persuader can achieve this bound arbitrarily closely by using strategies which tie all the problems together. We characterize this optimal payoff as a function of the information-theoretic capacity of the communication channel


Departments: Economics & Decision Sciences, GREGHEC (CNRS)

Stochastic independence has a complex status in probability theory. It is not part of the definition of a probability measure, but it is nonetheless an essential property for the mathematical development of this theory. Bayesian decision theorists such as Savage can be criticized for being silent about stochastic independence. From their current preference axioms, they can derive no more than the definitional properties of a probability measure. In a new framework of twofold uncertainty, we introduce preference axioms that entail not only these definitional properties, but also the stochastic independence of the two sources of uncertainty. This goes some way towards filling a curious lacuna in Bayesian decision theory.

Keywords: Stochastic Independence, Probabilistic Independence, Bayesian Decision Theory, Savage


Departments: Economics & Decision Sciences, GREGHEC (CNRS)

Agents make predictions based on similar past cases. The notion of similarity is itself learnt from experience by "second-order induction": past cases inform agents also about the relative importance of various attributes in judging similarity. However, there may be multiple "optimal" similarity functions for explaining past data. Moreover, the computation of the optimal similarity function is NP-Hard. We offer conditions under which rational agents who have access to the same observations are likely to converge on the same predictions, and conditions under which they may entertain different probabilistic beliefs.


Departments: Economics & Decision Sciences, GREGHEC (CNRS)

We argue that a precedent is important not only because it changes the relative frequency of a certain event, making it positive rather than zero, but also because it changes the way that relative frequencies are weighed. Specifically, agents assess probabilities of future events based on past occurrences, where not all of these occurrences are deemed equally relevant. More similar cases are weighed more heavily than less similar ones. Importantly, the similarity function is also learnt from experience by "second-order induction". The model can explain why a single precedent affects beliefs above and beyond its effect on relative frequencies, as well as why it is easier to establish reputation at the outset than to re-establish it after having lost it. Finally, we discuss more sophisticated forms of learning, by which similarity is defined not only on cases but also on attributes, and the importance of some attributes, learnt from the data by second-order induction, can also affect the perceived importance of other attributes.


Departments: Economics & Decision Sciences

This paper shows that bailouts of private agents can optimally take the form of asset purchases, even if this also means paying off external asset holders, in the presence of borrowing constraints and asymmetric information on liquidity needs. The combination of these two ingredients make direct compensation through loans and/or net transfers imperfect. Thus, when more constrained agents are also more exposed to the asset, the compensation through asset purchases becomes desirable. Anticipating these purchases, private agents engage in a collective bet on the defaulting asset, leading to an equilibrium implicit guarantee, where even an intrinsically worthless asset can be traded at a positive price

Keywords: Implicit guarantees, bailouts, capital ows, capital controls


Departments: Economics & Decision Sciences

We depart from Savage’s (1954) common state space assumption and introduce a model that allows for a subjective understanding of uncertainty. Within the revealed preference paradigm, we uniquely identify the agent’s subjective state space via her preferences conditional on incoming information. According to our representation, the agent’s subjective contingencies are coarser than the analyst’s states; she uses an additively separable utility with respect to her set of contingencies; and she adopts an updating rule that follows the Bayesian spirit but is limited by her perception of uncertainty. We illustrate our theory with an application to the Confirmatory Bias.

Keywords: understanding of uncertainty, subjective state space, non-Bayesian updating


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