https://www.reuters.com/article/us-facebook-results-stock/facebook-braces-for-stock-wipeout-as-lower-margins-loom-idUSKBN1KG1TN >Facebook Inc Chief Executive Officer Mark Zuckerberg's fortune is set to take a $16 billion hit on Thursday, as the social media giant braces for the biggest one-day wipeout in U.S. stock market history, a day after its executives forecast years of lower profit margins.