Analysing the behavioural finance impact of 'fake news' phenomena on financial markets: a representative agent model and empirical validation

This paper proposes an original behavioural finance representative agent model, to explain how fake news’ empirical price impacts can persist in finance despite contradicting the efficient-market hypothesis. The model reconciles empirically-observed price overreactions to fake news with empirically-observed price underreactions to real news, and predicts a novel secondary impact of fake news: that fake news in a security amplifies underreactions to subsequent real news for the security. Evaluating the model against a large-sample event study of the 2019 Chinese ADR Delisting Threat fake news and debunking event, this paper finds strong qualitative validation for its model’s dynamics and predictions.

Heterogeneous utility from a representative agent model: immigrants vs non-immigrants

Purpose The purpose of this paper is to infer the welfare of heterogeneous agents using a representative agent model. Design/methodology/approach It does so by partitioning the household into subunits and allocating consumption to each subunit proportionally to the income the subunit generates through wages and capital returns. Findings The author shows that for a simple dynamic general equilibrium model with immigration, the steady state utilities of these subunits correspond very closely to the utilities for an equivalent heterogeneous agent model. This is particularly true when labor–leisure decisions are made using slightly modified Euler equations. Originality/value More complicated models can be solved and simulated using fewer computational resources using this technique.

Can a Representative-Agent Model Represent a Heterogeneous-Agent Economy

Accounting for observed fluctuations in aggregate employment, consumption, and real wage using the optimality conditions of a representative household requires preferences that are incompatible with economic priors. In order to reconcile theory with data, we construct a model with heterogeneous agents whose decisions are difficult to aggregate because of incomplete capital markets and the indivisible nature of labor supply. If we were to explain the model-generated aggregate time series using decisions of a stand-in household, such a household must have a nonconcave or unstable utility as is often found with the aggregate US data. (JEL E13, E24)

The Value of Information in Efficient Risk-Sharing Arrangements

Suppose that agents share risks in competitive markets. We show that better information makes everyone worse off if the economy has a representative agent—that is, the economy's demand for state-contingent consumption equals the demand of a hypothetical agent who owns all the economy's wealth. The representative agent, moreover, is normatively unrepresentative: although each agent dislikes information, the “representative” agent is indifferent. Although we emphasize pure exchange, our results imply that a representative-agent model might seriously misstate the welfare effects of improved information in an economy with production and risk sharing, even if it performs well otherwise. (JEL D8)