Under pressure from Mark Zuckerberg and Sheryl Sandberg to monetize WhatsApp, he pushed back as Facebook questioned the encryption he’d helped build and laid the groundwork to show targeted ads and facilitate commercial messaging. Acton also walked away from Facebook a year before his final tranche of stock grants vested. “It was like, okay, well, you want to do these things I don"t want to do,” Acton says. “It’s better if I get out of your way. And I did.” It was perhaps the most expensive moral stand in history. Acton took a screenshot of the stock price on his way out the door—the decision cost him $850 million.