Crowdsourcing is a particular form of Open Innovation that aims to boost idea-generation in innovation processes. Its underlying rationale is that the collective intelligence of a large number of contributors increases the likelihood of collecting “extreme outcomes” i.e. exceptional ideas with high business potential. Although extant research has found evidence that crowdsourcing does indeed benefit innovation processes, its effect on firm performance has still to be verified. To this end, this work investigates the impact of crowdsourcing on stock market performance through an event study. Our findings evidence the boundary conditions, i.e. firm brand value and investment opportunities, under which crowdsourcing positively or negatively impact firm expected performance.