On January 1, California law said that all locally headquartered publicly traded companies must have at least one female director by 2020. While new to the U.S., mandates to increase gender diversity on corporate boards are common elsewhere. For example, Norway, Spain, France, and Iceland all have laws requiring that women comprise at least 40% of boards at publicly listed companies.

Evidence that board diversity benefits firms, however, has been mixed. A 2015 meta-analysis of 140 research studies of the relationship between female board representation and performance found a positive relationship with accounting returns, but no significant relationship with market performance. Other research has found no relationship to performance at all.

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