Acton was very critical of Facebook before resigning as Whatsapp CEO http://www.chicagotribune.com/business/ct-whatsapp-facebook-privacy-20180430-story.html
Upon further research, they were anonymous and it's as meaningful as 100 leaving the Republican party for one of Trump's cabinet appointments. They didn't actually appear to hold any actual power like the rest of the executives in this list which is also one of the reasons they resigned.
CEO of Groupe BPCE (France's fourth largest bank) resigned April 28th. He's going back to Rothschild & Co SCA to work with Alexandre de Rothschild. https://www.lesechos.fr/finance-marches/banque-assurances/0301615186916-francois-perol-demissionne-de-bpce-2172171.php
CEO of French aerospace company Zodiac Aerospace resigned effective June 16th, 2017.
http://www.zonebourse.com/ZODIAC-AEROSPACE-4729/actualite/Zodiac-Aerospace-M-Zarrouati-quittera-la-presidence-du-directoire-le-15-juin-24546671/
French telecom company Point Service Mobiles founder Martien Bocquillon resigned as CEO on 8/12/2017 https://www.channelnews.fr/martine-bocquillon-quitte-presidence-directoire-de-point-service-mobiles-78352
CEO of French investment company Wendel resigned September 7th 2017