https://www.theguardian.com/technology/2017/sep/27/mark-zuckerberg-facebook-2016-election-fake-news

Facebook founder, who called it ‘crazy’ to suggest misinformation on site affected voters, describes change of heart as company provides ad content to Congress

Mark Zuckerberg said he regretted dismissing concerns about the Facebook’s role in influencing the US presidential race, his latest acknowledgement that misinformation on the platform has affected elections.