The whopping $19 billion that Facebook is paying for the service is also unusual, even as other startups with no profit, or even revenue, are commanding sky-high valuations.
Koum and Acton are at the center of the largest buyout deal ever for a venture-backed company. How did two former Yahoo engineers who witnessed the late 90s dot-com boom - and bust - create the world's hottest app and make 10-year-old Facebook seem a tad grizzled?
"Jan keeps a note from Brian taped to his desk that reads "No Ads! No Games! No Gimmicks!' It serves as a daily reminder of their commitment to stay focused on building a pure messaging experience," wrote Sequoia Capital partner Jim Goetz in a blog post about Thursday's deal. Sequoia is WhatsApp's sole venture capital investor.
The Ukraine-born Koum, WhatsApp's CEO, move to the U.S. when he was 16. Acton was born in Michigan.