When does an app get too big to manage, both for the developer and the user? This is a problem Facebook recently faced. Facebook's current app is itself a collection of apps and native functionalities developed separately over time, and mostly for the desktop. Now on the tiny smartphone screen, all this functionality gets crowded and hard for the user to navigate. Mark Zuckerberg, founder of Facebook, has decided it is time to split Facebook up into more manageable apps that are linked to the main Facebook app, but are not a part of it. In this new strategy, Facebook becomes an app platform, not just a social network, that contains a wide variety of linked capabilities, which may, or may not, be branded as Facebook apps. It's a risky strategy that has investors worried.