How much did WhatsApp makers earn from Facebook acquisition?

WhatsApp founders Brian Acton and Jan Koum became billionaires in February 2014 when Facebook purchased their messaging service for $19 billion. While Acton earned $3.5 billion, Koum pocketed $6.8 billion and a Facebook board member seat from the deal. Acton and Koum, both former Yahoo employees, had incorporated WhatsApp eight years ago on February 24, 2009.