Voluntary contributions in a system with uncertain returns: a case of systemic risk

This paper investigates systemic risk that emerges from the interplay between uncertain returns to individual actions, uncertainty on others' behavior and all this filtered through individual attitudes toward risk. We design a finitely repeated linear public good experiment based on a voluntary contribution mechanism and analyze the effect of risky and uncertain returns on subjects' contributions. Results from a baseline treatment without uncertainty are compared with two risky treatments characterized by different values for the marginal per capita return. In the treatments with risk, subjects are randomly assigned to one out of three feasible marginal per capita returns, independently of what their individual contribution was. Results show that a sufficient level of uncertainty leads to significantly lower individual contributions. Furthermore, in a system with lower contributions due to uncertainty, subjects' risk aversion enhances the systemic risk, leading the system to collapse.