We combine new developments in decision theory with a standard consumption-based asset-pricing framework. In our model the efficient market hypothesis is violated if and only if agents' beliefs express ambiguity about the stochastic process driving economic fundamentals. Asset price fluctuations...

Why do people choose bank deposit contracts over a direct participation in asset markets? In their seminal paper, Diamond and Dybvig (1983) answer this question by claiming that bank deposit contracts can implement allocations that are welfare superior to asset markets equilibria. The present...

This paper models the empirical phenomenon of persistent fifty-fifty probability judgements within a dynamic non-additive Savage framework. To this purpose I construct a model of Bayesian learning such that an agent's probability judgement is characterized as the solution to a Choquet expected...

The Basel Committee on Banking Supervision sets the official confidence level at which a bank is supposed to absorb annual losses at 99.9%. However, due to an inconsistency between the notion of expected losses in the Vasicek model, on the one hand, and the practice of Basel regulation, on the...

Based on the axiomatic framework of Choquet decision theory, we develop a closed-form model of Bayesian learning with ambiguous beliefs about the mean of a normal distribution. In contrast to rational models of Bayesian learning the resulting Choquet Bayesian estimator results in a long-run bias...

Existing no trade results are based on the common prior assumption (CPA). This paper identifies a strictly weaker condition than the CPA under which speculative trade is impossible in a rational expectations equilibrium (REE). As our main finding, we demonstrate the impossibility of speculative...

This paper experimentally tests whether violations of Savage's (1954) subjective expected utility theory decrease if the ambiguity of an uncertain decision situation is reduced through statistical learning. Because our data does not show such a decrease, existing models which formalize ambiguity...

Individuals' subjective life-expectancy, as elicited in large-scale surveys, shows underestimation of survival chances at young versus overestimation at old ages. These distorted perceptions of objective survival chances may cause young people to save too little and old people to accumulate too...

The financial sector of emerging economies in Africa is characterized by a non-competitive banking sector which dominates any direct participation of agents in asset markets. Based on a variant of Diamond and Dybvig's (1983) model of financial intermediation, we formally explain both stylized...

This paper introduces an equilibrium concept for boundedly rational agents who base their demand-supply decisions on incorrect price anticipations. Formally, we differentiate between equilibrium and out-of-equilibrium states. If the agents attach zero prior probability to all out-of-equilibrium...