In November, I wrote about an academic study finding that companies experienced "a large negative stock market reaction" when Governor Jerry Brown signed into law California's female board quota mandate (SB 826).  The authors of this study recently provided me with some updated statistics regarding firm compliance:

"Prior to the signing of SB 826, there were 650 firms headquartered in California, of which 188 (29%) had zero female directors. The number of firms with all male boards declined to 21 by December 31, 2019."

They also found that seven firms with all male boards moved their principal executive offices out of California. 

The authors of the study are Daniel Greene and Vincent Intintoli, assistant professors of finance in the College of Business of Clemson University and Kathleen Kahle, professor of finance at the University of Arizona.   You will soon be able to read their study of the effect of SB 826 in “Do board gender quotas affect firm value? Evidence from California Senate Bill No. 826”, Journal of Corporate Finance, Vol. 60, February 2020.