Gender quotas, board diversity and spillover effects. Evidence from Italian banks

We study the impact of a law, which required the increase of the proportion of women on boards of listed companies to at least one third. We look at its impact on listed banks, but also test whether it led to spillovers into non-listed banks belonging to listed groups or along board diversity dimensions other than gender. Using administrative data, we compare diversity measures of boards of listed and non-listed banks in listed groups with those in non-listed groups, before and after the introduction of the law, in a difference-in-differences specification. We find that the gender quota law only changed the composition of the boards of listed banks, with no effects on their economic performance, nor relevant spillovers on other non-listed banks in listed groups. The law also enhanced diversity on boards of directors of listed banks along individual characteristics other than gender.