(Telecompaper) Facebook has agreed to buy the mobile messaging app WhatsApp for USD 19 billion. Facebook will pay USD 4 billion in cash and USD 12 billion in Facebook shares, and WhatsApp's founders and employees will also receive USD 3 billion in options on Facebook shares after closing the deal. This will give WhatsApp shareholders and staff in total 7.9 percent of Facebook's outstanding shares. Facebook will keep the WhatsApp brand, and the company's founder Jan Koum will join Facebook's board of directors. Similar to Instagram, WhatsApp will be allowed to operate independently within Facebook, maintaining its headquarters in Mountain View, California. Facebook will also continue to offer its own Messenger app, which will continue as a standalone application.