Jan Koum

broke to billionaire jan koum

Jan Koum was 16 when he immigrated to America from Ukraine with his mother. The two struggled in their new country, relying on government assistance to survive.

Koum taught himself computer networking as a teen, and as an adult, co-founded the messaging app WhatsApp, which Facebook bought this year for $19 billion. He signed the paperwork for the Facebook deal on the door of the welfare office where he once got food stamps.

First published June 5, 2014: 9:19 AM ET