In a surprise announcement, Facebook (NASDAQ: FB) CEO Mark Zuckerberg revealed yesterday that the social networking giant was losing two prominent executives: Chief Product Officer Chris Cox and WhatsApp chief Chris Daniels. The news shocked investors, who sent shares down in after-hours trading. With the exception of some high-profile exits of founders of acquired apps in recent years, Facebook's management team has been rather stable. This is a huge loss for Facebook. Chris Cox and Mark Zuckerberg. Image source: Facebook. Cox is Facebook's most important product exec In the note, His Zuckness said that Cox has for a few years expressed "his desire to do something else." Cox has been with the company for nearly 14 years, originally joining in 2005 as a News Feed engineer and working his way up to the highest echelons of the most powerful social networking company on Earth. Few executives at the company are as highly regarded. Cox is also a core part of Facebook's internal culture (he still regularly gives orientations to new hires). As part of Facebook's major restructuring last year, the company formed a "family of apps" division that included Facebook, WhatsApp, Messenger, and Instagram, with the leaders of all services reporting directly to Cox. Facebook says those core apps now have 2.7 billion monthly active users (MAUs). It sounds like Facebook's yearslong controversies have weighed on Cox, while the young executive isn't fully onboard with the company's newfound pivot to focus more on privacy. "But after 2016, we both realized we had too much important work to do to improve our products for society, and he stayed to help us work through these issues and help us chart a course for our family of apps going forward," Zuck wrote. In a statement to Bloomberg regarding the shift to privacy, Cox said, "This will be a big project and we will need leaders who are excited to see the new direction through." Fidji Simo will take over the Facebook app, and Facebook will not replace Cox. Instead, the leaders of all those services will report directly to Zuckerberg. WhatsApp gets a new chief...again WhatsApp co-founders Jan Koum and Brian Acton both left between 2017 and 2018, with Acton taking vocal opposition to the company he sold WhatsApp to. He renewed his call for people to delete Facebook just this week at a speaking appearance at Stanford. When Koum announced in May 2018 that he was leaving, Chris Daniels took over Facebook's most expensive acquisition ever. Daniels had previously been in charge of Facebook's Internet.org initiative, which aimed to bring internet connectivity to underserved regions. That means Daniels is leaving after less than a year as WhatsApp's chief, at a time when the service is still attempting to ramp up monetization while preparing to integrate with Facebook's other messaging services. Daniels "has helped define the business model for our messaging services going forward," according to Zuckerberg. Facebook's privacy-focused messaging strategy is about to pit the company against Apple like never before. Zuck named Will Cathcart the new head of WhatsApp. These are massive leadership changes at a time of considerable uncertainty for Facebook. No wonder investors are nervous. 10 stocks we like better than FacebookWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has quadrupled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Facebook wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of March 1, 2019Randi Zuckerberg, a former director of market development and spokeswoman for Facebook and sister to its CEO, Mark Zuckerberg, is a member of The Motley Fool's board of directors. Evan Niu, CFA owns shares of AAPL and Facebook. The Motley Fool owns shares of and recommends AAPL and Facebook. The Motley Fool has the following options: long January 2020 $150 calls on AAPL and short January 2020 $155 calls on AAPL. The Motley Fool has a disclosure policy.