Fake News in Social Networks Link to paper
Christoph Aymanns, Jakob Foerster, Co-Pierre Georg, and Matthias Weber. Research Paper No 22-58, Swiss Finance Institute.
We propose multi-agent reinforcement learning as a new method for modeling fake news in social networks. This method allows us to model human behavior in social networks both in unaccustomed populations and in populations that have adapted to the presence of fake news. In particular the latter is challenging for existing methods. We find that a fake-news attack is more effective if it targets highly connected people and people with weaker private information. Attacks are more effective when the disinformation is spread across several agents than when the disinformation is concentrated with more intensity on fewer agents. Furthermore, fake news spread less well in balanced networks than in clustered networks. We test a part of these findings in a human-subject experiment. The experimental evidence provides support for the predictions from the model. This suggests that our model is suitable to analyze the spread of fake news in social networks.
Intertemporal Prospect Theory Paper (PDF)
Immanuel Lampe and Matthias Weber. Working Papers on Finance No 2021/09, University of St. Gallen.
Note: We received the Vernon Smith Young Talent Award 2021 for this paper from the Society for Experimental Finance.
Prospect Theory is the most prominent contender of expected utility theory to describe decisions under risk. In atemporal contexts, prospect theory is well understood. In intertemporal contexts, however, it is not clear how prospect theory should be applied (in particular, whether probabilities should be weighted within time periods or whether the probabilities of present values should be weighted). It is also unclear what parametric specifications of probability-weighting and value functions should be used. We find in a pre-registered experiment on a representative sample that an application of prospect theory weighting probabilities of present values predicts decisions best. Estimated probability weighting functions are very similar to those typically estimated in atemporal settings, while value functions are almost linear with a loss aversion coefficient close to one.
The Role of the End Time in Experimental Asset Markets Paper (PDF)
Anita Kopányi-Peuker and Matthias Weber. Working Papers on Finance No 2021/12, University of St. Gallen.
By now there are hundreds of scientific articles on experimental asset markets. Almost all of these experiments use a short and definite horizon. This may be one of the starkest differences to financial asset markets outside the laboratory, which usually have indefinite and comparatively long horizons. We analyze the role of the end time in an asset market experiment in which we vary the length of the horizon and whether the end time is definite or indefinite. We find recurring bubbles and similar price dynamics in all treatments (with moderately lower prices in the treatments with a long horizon).
Credit Default Swap Regulation in Experimental Bond Markets Paper (PDF)
Matthias Weber, John Duffy, and Arthur Schram. Tinbergen Institute Discussion Paper 2019-039/I.
Credit default swaps (CDS) played an important role in the financial crisis of 2008. While CDS can be used to hedge risks, they can also be used for speculative purposes (as occurred during the financial crisis) and regulations have been proposed to limit such speculative use. Here, we provide the first controlled experiment analyzing the pricing of credit default swaps in a bond market subject to default risk. We further use the laboratory as a test bed to analyze CDS regulation. Our results show that the regulation achieves the goal of increasing the use of CDS for hedging purposes while reducing the use of CDS for speculation. This success does not come at the expense of lower bond IPO revenues and does not negatively affect CDS prices or bond prices in the secondary market.
Subsidies or Tax Breaks Versus Intellectual Property Rights: Dual Markets Link to paper
Egle Skliaustyte and Matthias Weber
Intellectual property rights are monopoly rights, which have undesirable welfare properties. Therefore, several studies suggest to use rewards as incentives for innovation instead. However, these studies have thus far had little effect on actual policy, possibly because such rewards may be difficult to implement in practice. We suggest a way of providing incentives to originators that is easy to implement. This is possible if there is an additional market in which the originator operates, where copying is not easily possible. Taking the music industry as example, copyrights in the records market could be replaced by subsidies or tax breaks in the market for live performances. We provide a modeling framework that can be used to analyze in which cases the replacement of intellectual property rights in one market with subsidies in another market is welfare improving or even pareto efficient.