 He was formerly employed at Yahoo!, and co-founded (with Jan Koum) WhatsApp, a mobile messaging application which was acquired by Facebook in February 2014 for US$19 billion.Acton left WhatsApp in September 2017 to start the Signal Foundation.According to "Forbes" (2019), Acton is the 836th-richest person in the world, with a net worth of $2.5 billion.