We prove that under very weak conditions optimal financial products have to be co-monotone with the inverted state price density. Optimality is meant in the sense of the maximization of an arbitrary preference model, e.g. Expected Utility Theory or Prospect Theory. The proof is based on methods...

We propose a new continuous time framework to study asset prices under learning and ambiguity aversion. In a partial information Lucas economy with time additive power utility, a discount for ambiguity arises if and only if the elasticity of intertemporal substitution (EIS) is above one. Then,...

The surge in international asset trade since the early 1990s has lead to renewed interest in models with international portfolio choice, an aspect that was largely cast aside when the ad-hoc portfolio balance models of the 1970s were replaced bymodels of optimizing agents. We develop the...

Seit Begründung der modernen Portfoliotheorie ist bekannt, daß die Portfoliovolatilität im Fall niedriger Korrelationen zwischen den Anlageklassen bei sonst gleich bleibenden Parametern ohne Renditeeinbuße reduziert wird...

Considered here is on-line portfolio management aimed at maximizing the long-run growth of financial wealth. The portfolio is repeatedly rebalanced in response to observed returns on diverse assets. Suppose statistical information and related methods are not available - or deemed too diffcult....

The paper shows that financial market equilibria need not exist if agents possess cumulative prospect theory preferences with piecewise-power value functions. The reason is an infiniteshort-selling problem. But even when a short-sell constraint is added, non-existence can occur due to...

This paper investigates model risk issues in the context of mean-variance portfolio selection. We analytically and numerically show that, under model misspecification, the use of statistically robust estimates instead of the widely used classical sample mean and covariance is highly beneficial...

We conduct controlled experiments in order to analyze individual trading behavior. Our results suggest that investors measure their gains relative to their initial wealth, and that this reference point together with past stock price changes determine the portfolio choices. Subjects choose a...

Control problems with Recursive Multiple-Priors Utility (RMPU) are highly non-linear so that RMPU asset prices have been studied in very simple exchange economies only. We identify a continuous-time exchange equilibrium with Locally-Constrained-Entropy RMPU (LCE-RMPU) that is tractable even in...