Wall Street JournalWhatsApp Co-Founder's 'Rest and Vest' Reward From Facebook: $450 MillionWall Street JournalAfter WhatsApp co-founder Jan Koum announced he was leaving Facebook Inc. FB -2.56% in late April, he has continued showing up at least monthly at the social-media giant's headquarters in Menlo Park, Calif. His incentive for making the appearances: ...The billionaire cofounder of WhatsApp is 'resting and vesting' — showing up to Facebook and barely working to ...Business Insiderall 10 news articles »