https://www.theguardian.com/technology/2018/jul/25/facebook-stocks-second-quarter-revenue-user-growth

Company warns of slowing revenue growth as it invests in security – but it still makes $13.2bn

Facebook stock price tumbled more than 20% in after-hours trading, after the company’s chief financial officer said revenue growth would “continue to decelerate in the second half of 2018” as the company increased its investment in security and privacy.